SCons build system files added.

You'll need SCons (www.scons.org) to build.
Platforms currently working:
* Linux (me)
  - options for quicktime, openal and international disabled
  - uses the system libs and include files for building - no option to build
    with the precompiled libraries yet.
* Windows (jesterKing)
  - builds with quicktime (optional)
  - builds with openal (optional)
  - builds with international support (optional)
  - Use the DOS box to build
  - builds with precompiled libraries
* Irix (Hos)
  - Uses default Irix compiler
  - Not all optimization levels correct yet
  - options for quicktime, openal and international disabled
  - builds with precompiled libraries
* Cygwin (me)
  - has a problem in the linking stage
  - uses free build tools (gcc)
  - options for quicktime, openal and international disabled
  - uses the system libs and include files for building - no option to build
    with the precompiled libraries yet.
* MacOS (sgefant)
  - builds with quicktime (optional)
  - options for openal and international disabled
  - builds a nice bundle
  - builds with precompiled libraries

Thanks to IanWill for a bugfix in the Linux build.
Note: This is a work in progress. A lot still has to be done - for example the
      optional parts are only to be enabled by directly setting 'true' or
      'false' in the SConstruct file. This needs to be moved to a user config
      file. Also, the .o/.obj files are stored in the source tree. This needs
      to be fixed as well.
      The game engine is not yet built.

intern/SConscript

@@ -0,0 +1,11 @@
+SConscript(['SoundSystem/SConscript',
+            'string/SConscript',
+            'ghost/SConscript',
+            'guardedalloc/SConscript',
+            'bmfont/SConscript',
+            'moto/SConscript',
+            'container/SConscript',
+            'memutil/SConscript/',
+            'decimation/SConscript',
+            'bsp/SConscript',
+            'iksolver/SConscript'])