CharArray should always be null-terminated. There is a potential
scenario where this all might lead to crash. In Password we call
memset(), passing length of the array we get with strlen(), but
this won't return correct value when the array is not properly
null-terminated.

Give people a chance to know about the documentation.

It's almost mandatory to specify "session", but fairly rare to need to
set "desktop", so let's tweak the examples to avoid confusion and
mistakes.

Build flags control where this file ends up, so avoid assuming a
specific path in the HOWTO.

The line width was very inconsitent in this file, so standardise on the
common 72 characters.

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.

Incorrect format strings can cause crashes, so we want to catch those
early.

Trying to dynamically track the DPI did not really work as we'd
start accumulating errors and eventually the DPI would start to
drift. Instead maintain a fixed, sensible DPI at all times.

Thanks @Raulkumar for finding this in #1118

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!

stderr has been redirected to /dev/null so all logging needs to go to
syslog.

This change adds support for the VMware Mouse Position
pseudo-encoding[1], which is used to notify VNC clients when X11 clients
call `XWarpPointer()`[2]. This function is called by SDL (and other
similar libraries)  when they detect that the server does not support
native relative motion, like some RFB clients.

With this, RFB clients can choose to adjust the local cursor position
under certain circumstances to match what the server has set. For
instance, if pointer lock has been enabled on the client's machine and
the cursor is not being drawn locally, the local position of the cursor
is irrelevant, so the RFB client can use what the server sends as the
canonical absolute position of the cursor. This ultimately enables the
possibility of games (especially FPS games) to behave how users expect
(if the clients implement the corresponding change).

Part of: #619

1: https://github.com/rfbproto/rfbproto/blob/master/rfbproto.rst#vmware-cursor-position-pseudo-encoding
2: https://tronche.com/gui/x/xlib/input/XWarpPointer.html
3: https://hg.libsdl.org/SDL/file/28e3b60e2131/src/events/SDL_mouse.c#l804

Or rpmbuild gets grumpy.

This reverts commit d6e39658ae. Apparently
this is broken on macOS so it's not something we can make use of.

Some of these were incorrectly calculated so the server or client would
wait too long before proceeding with decoding.

Change all of these to be a more explicit calculation to avoid such
issues in the future.

TCP_CORK is a Linux thing and BSD has TCP_NOPUSH instead.

We didn't include the proper headers to get the correct define, so
corking was never enabled.

Otherwise we might end up owners of something we cannot deliver data on,
which can hang applications.

Setting `rfbport` to `-1` disables TCP port listening.

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.

So that people can easily find them and not file bug reports for
things that are just questions.

We want users to use the templates so we don't miss any relevant
information.

We computed a safe area if a client gave us a bogus one, but we didn't
actually use it. Fix this properly and make sure we don't pass on bad
coordinates further.

So the current clipboard state is properly reflected in the desktop
session.

This was out of sync with the client handling for no good reason.

The peer expects a response, so we should also be able to respond that
there is no clipboard data currently available.

The extended clipboard protocol has the ability for the peer to request
things to be sent automatically, without a request message. Make sure we
honor such settings.