added player_id_t typedef and INVALID_PLAYER, use that instead of -1.
also added sanity checks to cpu.cpp to ensure ARCH_* is correct (see
http://www.wildfiregames.com/forum/index.php?showtopic=13327&hl=)
and further predefined macros to arch.h just to be sure.
This was SVN commit r8079.
Don't call xmlCleanupParser after parsing documents.
("This function name is somewhat misleading. It does not clean up parser
state, it cleans up memory allocated by the library itself.")
This was SVN commit r7465.
Moved skeleton definitions into XML format, to support multiple
different structures. (Not quite finished yet.)
Added support for rescaled models in XSI.
Minor refactoring.
This was SVN commit r4959.
