Follow upstream FLTK naming to more clearly indicate that this is a
general widget and not TigerVNC specific.

These are general things and not specific to TigerVNC, so let's move it
to the fltk specific directory for clarity.

These have nothing to do with layout, so let's split them to their own
file.

Let's separate TigerVNC specific things from stuff that could be part of
upstream FLTK. These are files that we would like to collaborate with
other FLTK users, so they are more liberally licensed and avoid using
TigerVNC specific things.

This is to make the code more tolerant of typos when entering a hostname

It is generally pulled in as a requirement from GnuTLS, but let's be
explicitly now that we make use of nettle directly.

pkg-config support was added very recently to gmp, so a lot of platforms
we want to support won't find gmp this way.

It is a (weird) dependency of nettle, and not part of nettle itself. So
split it to a separate module for clarity.

The order is important in the servers, so make sure the man pages follow
the code properly.

This was accidentally disabled in 81e114f.

This call should have been preceeded by hasData() or avail(), just like
all other accessor functions.

We should scope these as narrowely as possible to avoid side effects.

Avoid duplicating all the memory mangement, and instead use the
BufferedOutStream as a base clase for all out streams that need an
intermediate buffer.

Allow subclasses to call it, instead of it being strictly internal. This
is useful when a subclass can only provide data in minimum sized chunks.

It might not be compiled in, so the height needs to be dynamic.

We lacked an entry for one of these, and the magical swap that macOS
does for unknown reasons.

Makes it easier to compare changes with what people normally run.

Add also missing <stdlib.h> where required.

Fix edge of dot cursor in Java vncviewer

This commit changes the color of the edges of the dot cursor in the Java
version of vncviewer from fully transparent to white, bringing it in
line with the C++ native version.

Might be useful for testing in some cases. Note that the Windows and
Linux binaries will depend on libraries from the build environment. So
the user will need to match those manually.

The previous commit was incorrect in that it overrides automake's
dependency list, rather than adding to it. So we need to make sure
things are duplicated between Xvnc_DEPENDENCIES and Xvnc_LDADD as
appropriate.

Use the same approach as the Xorg binary to keep things familiar.

These aren't crucial for a clean build, but must be set for Xvnc to be
properly rebuilt if anything in the Xorg tree changes. automake doesn't
properly deduce these automatically from Xvnc_LDADD, unfortunately.

The socket might not be the stream actually used, e.g. when we are using
TLS. Make sure we cork the proper stream to get all the benefits of
corking.

Avoid having to buffer everything we want to discard, and instead do it
piece by piece. This is more efficient, and avoids hitting any limits on
the buffering.

Note that this is safe here because we already know we have all the
compressed data. It would not be safe for a general input stream.

These streams both need to change the corking state temporarily, but it
is important it is restored to the previous state or things might get
messed up.

For the zlib stream it would just leave things uncorked, which still
works but is less efficient.

But for the TLS stream it might make things very unresponsive as the
corking might be left on permanently, delaying packets indefinitely.

Uncorking implicitly flushes, so we don't need this.

There is no point flushing when corking was enabled, as we might then
push out a small buffer that the corking otherwise would have preserved.

It seems MFT h264 decoder does not support frame cropping. Which
means that if frame width or height is not multiple of 16 then
decoded output can potentially be used with wrong offset. This
code adds explicit parsing of SPS to extract cropping information
to use, and will apply cropping if reported size differs from
expected.

This is the standard method of finding it on Unix systems, so make sure
we use it. Still keep a fallback, though, for other systems, e.g.
Windows.

FFMPEG is needed by the RFB library, so all the details about it should
only be applied there and not for other components.

This is the standard method of finding it on Unix systems, so make sure
we use it. Still keep a fallback, though, for other systems, e.g.
Windows.

We need this function to deal with pkgconfig files properly, but
unfortunately it doesn't exist until CMake 3.13, and we need to support
CMake 3.10. So add a hacky compatibility function for older systems.

Modern cmake has better support for adding source files and libraries
incrementally, so let's use that to clean things up.

Our embedded zlib got removed way back in cc8c6a2.

Reduce the icon margins a bit to conform better with other icons. Also
dial back the rounding a bit, again to fit better with other programs.