added trace.realfraction field which is now used for comparisons instead of fraction...

added trace.realfraction field which is now used for comparisons instead of fraction, this allows proper detection of the nearest blocker without the glitches previously seen sometimes on brush-brush boundaries (where the expanded side boundary was closer than the floor it was part of)
optimized q3bsp point traces (point, not line)
optimized q3bsp line traces (finally got that code working, and added optimized line-triangle tracing code for curves which is 52% faster)
optimized q3bsp brush traces (or tried to...  seems to be slower unfortunately, more work to do on this in the future)
BrushForBox now sets the mins/maxs of the brush for culling
reduced q3mnode_t structure by 4 bytes (checks plane pointer now instead of a dedicated isnode variable)
cleaned up some collision code a bit
added some TargetQuake workarounds (spew warnings instead of crashing to console) for weird physics settings (like MOVETYPE_PUSH and SOLID_BSP with no model)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@3853 d7cf8633-e32d-0410-b094-e92efae38249