The normal case was to use the builtin icons. There were two cases
where the icon file was read from disk:

1) /usr/NX/share/images/nxagent.xpm was existing which normally is not
   there

2) case 2 was not true and nxagent.xpm was existing somewhere in the
   PATH (!)

(replace nxagent.xpm by x2goagent.xpm if in x2gp mode)

Scanning the path from the PATH variable for xpm files is kind of
unexpected and dangerous, too (think of automounter triggers or
invalid xpm files).

Also remove the xpm files from the distribution.

 Fixes ArcticaProject/nx-libs#546.

Makefile: Align variable names USRLIBDIR, SHLIBDIR (and NX_DIR) with nx-X11 internal naming schemes (and use /usr/<lib>/nx/X11 rather than /usr/<lib>/nx-X11).

Makefile: Align variable names USRLIBDIR, SHLIBDIR (and NX_DIR) with nx-X11 internal naming schemes (and use /usr/<lib>/nx/X11 rather than /usr/<lib>/nx-X11).

  o Install nxagent/nxproxy executables into multi-arch path.
  o Fake libNX_X11.so* as $LIBDIR/nx-X11/libX11.so*.
  o Allow injecting different $NXAPP containing the executable name.

  o For e.g. x2goagent this requires the following changes:

    - Move x2goagent symlink from /usr/lib/x2go/bin/x2goagent to
      $LIBDIR/nx/bin/x2goagent
    - Replace /usr/bin/x2goagent by a two-liner...

    ```
    #!/bin/sh

    export NXAPP=x2goagent
    nxagent
    ```

 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.

  * 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.

Provide a default keystrokes.cfg in /etc/nx (for nxagent) and /etc/x2go (for x2goagent). (Fixes: #199).

Drop patch 032, fix other patches so that installation via make install installs NX components to /usr/local/lib/nx and /usr/local/include/nx.

  - 005_add-nxagent-wrapper.patch.
  - 008_add-nxproxy-wrapper.patch.
  - 011_add-nxauth-wrapper.patch.

  - 101_nxagent_set-rgb-path.patch
  - 102_xserver-xext_set-securitypolicy-path.patch
  - 103_nxagent_set-X0-config-path.patch
  - 104_nxagent_enable_debug.patch
  - 105_nxagent_export-remote-keyboard-config.patch
  - 106_nxagent_utf8-copy-clipboard.patch
  - 107_nxagent_clipboard-compound-text+small-bed-sheets.patch
  - 108_nxagent_wine-close-delay.patch
  - 109_nxagent_locale-utf8-compound-text.patch
  - 200_nxagent_unbrand-agent.patch