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.
Merge from 22b478ffed8d.
Pure scripted interface definitions.
Entity creation from scripts.
Improved messaging system.
Messages on entity deletion.
Basic player entities.
Player ownership.
Bug fixes.
This was SVN commit r7281.