Blender Git Loki

Logic Editor: removing usercount for existent datablocks

Using custom setfuncs to avoid increase/decrease of usercount.
That way nothing stops you from removing a material that is used by a
sensor, or a mesh, an action ... (this is how 2.49 works too)

* also some general code cleaning/fix (adding static casts, replacing libaddr_us by lib_addr for dome text (I had no idea how user count worked back then)