It was GPL3 instead of GPL2!

Fixes ArcticaProject/nx-libs#112

This commit removes TextCompressor class references from ClientCache
and ServerCache as it's no longer used after removing old protocol's
compatibility code from nxcomp. It also removes the attribute textCache
from both classes as it's no longer used either.

Finally the header and source files associated with the TextCompressor
class are also deleted and removed from the compilation process.

Refs: ArcticaProject/nx-libs#108

This commit provides documentation about some error tests that have been
run to check how well behaves nxcomp after removing it's compatibility
code with versions prior to 3.5.0 and it has to handle a situation in
in which and older proxy tries to connect with a nxcomp 3.6.x based proxy.

Refs: ArcticaProject/nx-libs#108

This commit removes obsolete compatibility files whose components were
only used to handle compatibility with old protocol versions that are
no longer supported.

Refs: ArcticaProject/nx-libs#108

As a part of nxcomp's clean-up process, compatibility with old protocol
versions has been set now at 3.5.0.

This commit removes compatibility code from nxcomp so the minimum supported
version changes from 1.5.0 (protocol step 6) to 3.5.0 (protocol step 10).

At this moment the removal is not complete and it will be followed by some
other commits, in order to get rid of several components and files that are
no longer used as they were only needed to work with old protocol versions.

Refs: ArcticaProject/nx-libs#108

Fixes ArcticaProject/nx-libs#104

debian/patches/401_nxcomp_bigrequests-and-genericevent-extensions.full+lite.patch: Move into debian/patches-pending-evaluation/.

Attributes GH PR #71: https://github.com/ArcticaProject/nx-libs/pull/71

Add instructions for building using Mock under Fedora/EPEL.

debian/nx-x11proto-xinerama-dev.install.in: Install PANORAMIX extension header files into its own nx-x11proto bin:package. (more Xinerama clean-up, fix FTBFS during dh_install).

Complete changes from commit 0d56c45a in NXpicturestr.h (i.e. add a missing comment).  (Fixes ArcticaProject/nx-libs#38).

commit 0d56c45a was:
nx-X11: handle source pictures (those without a Drawable surface) gracefully.

Attributes GH PR #66: https://github.com/ArcticaProject/nx-libs/pull/66

This fixes the problem Mike Gabriel describes like this:

- Launch a session on a system with a single monitor. Enable Xinerama
  for this session.
- Open a desktop session in that session window (e.g. MATE or XFCE).
- Move the NX/MATE-or-XFCE session window around on that one
  monitor. Bump at the borders, so that the session window moves into
  the invisible parts around your monitor.

What you see is that the MATE-or-XFCE window manager will become
really busy with resizing the windows and panels in the NX session,
because moving the window over the physical borders of the display
will trigger resize events.

This is non-intuitive, I think.

Same with multi-monitors on the outside edges of the physical Xorg
RandR setup.

X2Go Agent: Add x2goagent.features file that informs X2Go clients about the new RandR based Xinerama feature.

 By design, when resuming a session, Xinerama can only be re-enabled
 by NX option parsing.

 Thus, this change introduces a "xinerama" NX option that can
 be loaded via an options file into NX agent when resuming
 a session. The new xinerame NX session option also allows
 switching on Xinerama at session startup via an option file.

 When implementing the new NX Xinerama support into clients (like
 TheQVD, X2Go Client, etc., this new xinerama NX option should be
 used for activating Xinerama in the NX / QVD / X2Go session.

Initialize XRandR based Xinerama extension properly when session is started with "-geometry fullscreen".