got rid of AreaNode stuff, now only has AreaGrid (had to add sv_areagrid_outside...

got rid of AreaNode stuff, now only has AreaGrid (had to add sv_areagrid_outside node)
renamed sv_useareanodes to sv_debugmove (inverted behavior)
SV_CreateAreaGrid now has a minimum grid size (sv_areagrid_mingridsize cvar), this greatly improved performance in helm18
SV_ClipToAreaGrid and SV_TouchAreaGrid no longer process any edicts twice (edict_t now has areagridmarknumber for this purpose)
increased AREA_GRID from 16 to 512
added SV_ClipToNode function to get rid of duplicate code in SV_ClipToAreaGrid

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@2809 d7cf8633-e32d-0410-b094-e92efae38249