- Update XErrorDB to latest X.org version.
  - Install XErrorDB, XKeysymDB and Xcms.txt to /usr/{local/}share/nx/.
  - Assure that libNX_X11 finds those files at the
    named location.
  - Update debian/ packaging files.
  - Update nx-libs.spec packaging file.

Fixes ArcticaProject/nx-libs#153

library clean-up: Don't build libNX_Xinerama anymore. Use system's libXinerama shared library. (Fixes ArcticaProject/nx-libs#49).

 This commit goes along with a patch from Ulrich Sibiller who managed to
 move the Xinerama awareness for NX sessions into the Xserver code. This
 makes Xinerama support for NX in libNX_Xinerama.so obsolete.

 Fixes ArcticaProject/nx-libs#49

  * 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.