roll-tarballs.sh: Adapt to recent changes in nx-libs, keep legacy support for older 3.6.x and 3.5.x releases.

 Fixes ArcticaProject/nx-libs#276.

roll-tarball.sh: Don't ship doc/X11-symbols/ in the lite (proxy-only) tarball derived from the nx-libs code tree.

 The x2goagent package is being replaced by an x2goserver bin:package
 named x2goserver-x2goagent.

 This x2goserver-x2goagent bin:package will be maintained in the X2Go
 Project's namespace and basically wraps around nxagent.

 Furthermore, declare Arctica Project as upstream source for nx-libs.

 As the system a tarball gets extracted on may potentially be unable
 to handle symlinks, we ship symlinks as files in the rolled tarball.

 By transforming symlinks into real files, we also assure that all
 VERSION files/symlinks get shipped in the tarballs.

 Fixes ArcticaProject/nx-libs#27

debian/roll-tarball.sh: Rename README.md to README.NX-Development before moving it into doc/ folder.

* bin/{nxagent,nxauth,x2goagent}
* etc/
* doc/nx-X11_vs_XOrg69_patches
* README.keystrokes"
* nx-libs.spec

debian/roll-tarball.sh: Allow patch files names having a dash next to the four digits (i.e., 1234-<patchname>.<suffix>).

 As the system a tarball gets extracted on may potentially be unable
 to handle symlinks, we ship symlinks as files in the rolled tarball.

 By transforming symlinks into real files, we also assure that all
 VERSION files/symlinks get shipped in the tarballs.

 Fixes ArcticaProject/nx-libs#27

debian/roll-tarball.sh: Rename README.md to README.NX-Development before moving it into doc/ folder.

* bin/{nxagent,nxauth,x2goagent}
* etc/
* doc/nx-X11_vs_XOrg69_patches
* README.keystrokes"
* nx-libs.spec

debian/roll-tarball.sh: Allow patch files names having a dash next to the four digits (i.e., 1234-<patchname>.<suffix>).

Worked out fine so far, because the next line was empty, but this can
easily change...

Prevents random characters as being treated as part of a variable name.

Fixes potential bugs, including one triggered by an unquoted hash within
the command line. BASH accepts this. Other shells do not (i.e., treat
everything following the hash character as a comment.)

  Adapted packaging scripts:

   debian/roll-tarballs.sh
   nx-libs.spec

  Affected packagings scripts:

    debian/roll-tarballs.sh
    debian/rules
    nx-libs.spec

  The installation process copies NX wrapper scripts into
  $(srcbase)/bin/ before build time.

  Those wrapper scripts are now in place natively and need not
  to be copied prior to building NX.

  Packaging scripts with adaptation:

   debian/roll-tarballs.sh
   debian/rules
   debian/*.docs
   nx-libs.spec

  This makes it obsolete to add changes to debian/changelog. We document
  our changes in Git (3.6.x branch and other related branches). On
  release, we generate an upstream ChangeLog from Git history.

  Only on the 3.5.0.x, we continue maintaining our changes in
  debian/changelog (to be compliant with current nx-libs release workflow
  in X2Go).

  The following packaging scripts needed adaptations to this change:

    debian/roll-tarballs.sh
    debian/rules
    nx-libs.spec

VERSION file: master VERSION file is in base folder, symlinked from nx*/VERSION and hw/nxagent/VERSION.

  This commit removes the debian/VERSION file at makes it now unnecessary to
  copy/symlink the VERSION file at build time. These build scripts got adapted:

    debian/roll-tarballs.sh
    debian/rules
    nx-libs.spec

  Furthermore, all NX component now use the main VERSION file as reference.

    typechange: nxcomp/VERSION
    typechange: nxcompext/VERSION
    typechange: nxcompshad/VERSION
    typechange: nxproxy/VERSION

    debian/roll-tarballs.sh
    debian/rules
    nx-libs.spec

Unify source tree reduction (debian/rules vs. roll-tarball.sh) via file/folder lists in text files named debian/CODE-REDUCTION_*.

debian/roll-tarball.sh: Install etc/ files into etc/ subfolder (rgb, nxagent.keyboard, x2goagent.keyboard).

  * Debian/Ubuntu packaging:
    + Fully rework the way nx-libs gets packaged for Debian/Ubuntu.
    + Split up libnx-x11 into individual packages.
    + Provide dbg:packages for each bin:package containing binaries.
    + Use Makefile logic to install files into DESTDIR.
    + Provide dev:packages for each lib:package individually.
    + Provide nx-x11proto-*-dev packages for all libnx-* libraries.
    + Install _all_ library files (*.so*) to /usr/lib/<triplet>/, so
      no extra settings of LD_LIBRARY_PATH is necessary.

More source tree size reduction by analyzing what exactly of the Mesa source code in nx-X11/extras/ is used and what not.

* Drop more unused folders from tarball release / before .deb package build:
    - nx-X11/programs/Xserver/miext/shadow/
    - nx-X11/programs/Xserver/XpConfig/
    - nx-X11/programs/Xserver/Xprint/