Bug introduced in fb561eb but still somehow passed manual testing.
Resulted in some stray reads off the end of the stack, which were
hopefully harmless.

These function are not guaranteed to succeed, and we've had reports that
they fail on ARM. So make sure we more properly check return values.

Try to be more consistent that related options should have a group box
around them.

This is what pretty much everyone else calls these kind of settings, so
let's change so users feel familiar.

Try to focus on the commonly used settings here in order to keep things
understandable. The uncommon settings will need to be specified as
command line arguments instead.

Clarify what this list is used for, and organize it so it is easier to
match to the options dialog.

Previously, there were a number of inconsistencies in the use of
"full-screen" and "full screen" in logs, documentation, and user
interfaces. The consensus seems to be that "full screen" is correct when
used as a noun while "full-screen" is correct when used as an
adjective. These inconsistencies have now been adjusted to follow
consensus.

vncviewer previously had a the same localized error message duplicated
on a bunch of places. Pull these duplicates out into a single function.

If you close the reconnect dialog then we should assume that you want to
close things, not that you want to reconnect. Unfortunately FLTK returns
the first choice when closing the dialog, so that needs to be the
"Cancel" alternative.

FLTK's fullscreen_x() function will always put the window on a high
level (NSStatusWindowLevel = 25), even if the window doesn't have focus.
This causes the OptionsDialog to end up behind the DesktopWindow when
the fullscreen function is called. Until we can rest assured that most
people building TigerVNC will use a fixed version of FLTK, we will need
this workaround.

Modal windows are meant to be child windows such as menus or popups that
are intended to always appear in front of its parent.

Modal FLTK windows without a parent seem to behave strangely on macOS.
Such windows can appear in front of their modal children windows.
When opening OptionsDialog from ServerDialog, it was easy to get to a
broken state by then switching focus back to the ServerDialog. This
would cause the ServerDialog to appear in front, but not be useable as
the options window would still have control of mouse and keyboard.

Additionally, modal windows without parents appear in front of other
normal applications on macOS. This means that the ServerDialog couldn't
be put behind Safari for example.

The fact that ServerDialog was a "modal" window was a bit strange,
seeing as it doesn't have any parent windows. Removing the modal
property from this window causes all the strange-ness to go away.

There was an issue with the new grabs that were introduced in commit
2289342de7. On macOS when running
vncviewer in fullscreen on one monitor, we saw that we sometimes got
resize and fullscreen events when switching the focus away from
vncviewer. With the changes in the commit mentioned above this meant
that we immediately grabbed the keyboard again, thus never releasing it.

Fixes #1332.

If a monitor is part of a set of mirrored monitors, then give the name
of all used monitors as we don't know which one the user will most
strongly associate with what they see.

The device name is very internal and likely of little use to a user.
Instead give the more user friendly string we can get out of the system.

Makes it a lot easier to deal with the allocation of memory for the
string, avoiding any limits.

It's just used in this one place, and isn't very large. Also move things
around a bit to avoid having to define new complex types.

Fix a bug in the comparison function that could result in the wrong
index being assigned to a monitor. Change the logic to more directly map
to the description.

macOS and Windows present mirrored monitors as a single virtual monitor,
but X11 exposes this scenario as two distinct monitors with identical
coordinates. This messes up our logic, and is likely confusing for the
user. So instead we'll ignore any monitors that have identical
coordinates to any already seen monitors.

Try to reuse and split things so that it makes things easier for the
translators.

Clean up the structure around storing and loading parameters and server
history so that failures will always be reported by using exceptions.

Error handling is more straight forward in the C file interface.

Let's separate the standard global event handling from the hacky
workarounds, for clarity.

If the file has been transferred from a Windows system then it might
have \r\n line endings instead of \n. Make sure this doesn't leak in to
the parameter values.

We only need to check the event type once, and preferably early, and
avoid doing more work than necessary.

We don't want the log to spam every time this parameter is used so only
complain from the parses when the value is changed.

This class is generic and should not reference a specific instance of
it.

Try to be consistent with existing log messages.

Fix some indentation issues and make sure everything* uses CamelCase.

* MonitorArrangement is left as snake_case in order to pretend it is an
  independent FLTK widget class.

MonitorArrangement (in the options dialog) never changes when the system
monitor configuration changes. Therefore, the user can get into a state
where the reality doesn't match what is shown (when a monitor is
added/removed, resolution or position changed etc).

All these changes triggers an event in FLTK
(FL_SCREEN_CONFIGURATION_CHANGED). This commit adds an event handler in
MonitorArrangement and refreshes the widget whenever that event occurs.

Because Fl_Handler does not have a void*-argument (and we must be able
to access the widget from our handler callback) a static set of
instances have been added, which all will receive the events.

It might be useful to have more information about a monitor when
configuring its settings in the Options menu. Therefore, this commit
adds support for showing additional information about a monitor
(resolution and platform-specific name).

There are no guarantees from the WM that calling `fullscreen_screens`
with all monitor indices set to `-1` results in the window's current
monitor being used. Because FullScreenMode uses the word "current"
we want to explicitly ask the WM to use that monitor.

The user might not always want to use all monitors when in fullscreen
mode, but instead only a few. This commit adds support for configuring
selected monitors from command line, in the config file and graphically
in the options menu.

Because it might be hard to guarantee the consistency of monitor
identifiers coming from third-parties (for example FLTK), it has been
decided to use our own numerical identifier. This identifier is based on
the monitor's positions. The mapping between this identifier and the
indices used by FLTK is done by MonitorIndicesParameter.

Before this commit, `FullScreen` and `FullScreenAllMonitors` could be
used to configure whether to use the current monitor in fullscreen,
or all monitors in fullscreen.

This commit deprecates `FullScreenAllMonitors` in favour of
`FullScreenMode` (which can either be `current` or `all`). This allows
for additional modes to be added, without the risk of having invalid
states (for example two activate two different fullscreen modes at the
same time).

A new concept has been added; read-only parameters. They are parameters
that will be read, but never written back. This allows for migration
paths to be constructed, where a parameter can be taken to consideration
but then for example be discarded, logged or changed into something else.

This has been used for `FullScreenAllMonitors` to provide a migration
path. On startup of vncviewer, if `FullScreenAllMonitors` is enabled,
`FullScreenMode=all` will be automatically enabled instead. The next
time the configuration file is written to disk, `FullScreenAllMonitors`
will then be removed.

Previously, it was assumed that all monitors (and especially the primary
monitor, index 0) was inside the window when we calculate the position
of the overlay.

That might not always be the case, for example when using fullscreen
mode over a narrower set of monitors. This commit does so the overlay is
positioned correctly based on the actual window size, instead of what we
expect it to be.

cocoa_capture_displays it captures all displays enclosed by the
window_rect. If a set of displays were captured, but the configuration of
what monitors to use changed, a second call would only add to the set
of captured displays. Therefore, if the user enabled
FullScreenAllMonitors (all displays captured) and then disabled it (only
one display captured) they would get into a state were monitors not used
for the VNC session still were captured (which on macOS for example,
results in displays being unusable for other things).

This has now been fixed, resulting in monitors outside the window_rect
not being unnecessarily captured.

It was only possible to capture either the current, or all displays
previously. This could become an issue if you want to show a vnc session
over only a selected set of displays, because then we only want to
capture those displays.

The solution in the commit was chosen because it handles all cases - by
looking at what monitors are enclosed by the viewport the implementation
is independent on any configuration, but instead captures the monitors
actually being used.

Let's avoid making this too complex and force every user to know about
magical functions.

The old method used a very slow frame rate with small steps,
which made it obnoxious during use.  The new method has a few
improvements:

- Calculates "edge" region width automatically, as a ratio of
  the viewport size.  Default is 1/16th.

- Uses a different edge width for x and y, which works better
  on very wide or very tall screens.

- Increased default frame rate from 10 fps to 60 fps.

- Replaced hardcoded frame rate with a #define.

- Reduced maximum movement per frame slightly, because the
  frame rate is so much faster.  The overall result is still much
  faster, but also easier to do small adjustments with.

- Fixed off-by-one error in scroll rate calculation formula.  Left/up
  scrolls were faster than down/right, but this is fixed.

This makes it more comfortable to use TigerVNC on a small screen
to work on a larger screen for hours at a time.

This change makes it possible for re-synchronizing the remote cursor on
the vncviewer when in fullscreen mode. This is done by locally moving
the cursor position to what the server thinks it should be.

Now SDL games should work!

It took way too long to converge on a sane value, so reduce the window
by a factor of ten. This seems to work smoothly.