* the temporary checking arrays are now static
* the array that gets the returned values only starts allocating memory when the third touched sector group is found. The most common cases (no touched portal and one touched portal) can be handled without accessing the heap.
- did some streamlining of AActor::LinkToSector:
* there's only now version of this function that can handle everything
* moved the FIXMAPTHINGPOS stuff into a separate function.
* removed LinkToWorldForMapThing and put all special handling this function did into P_PointInSectorBuggy.
This was to resolve some circular dependencies with the portal code.
The most notable changees:
* FTextureID was moved from textures.h to doomtype.h because it is frequently needed in files that don't want to do anything with actual textures.
* split off the parts from p_maputl into a separate header.
* consolidated all blockmap related data into p_blockmap.h
* split off the polyobject parts into po_man.h
