fixed grenades to behave more like quake again (60 normal-dot-velocity tolerance...

fixed grenades to behave more like quake again (60 normal-dot-velocity tolerance for stopping), fixed continuous bounce sound (repeated touch when sitting on floor), you can now walk on SOLID_SLIDEBOX/SOLID_BBOX objects (like in Q2/Q3), if two objects are stacked and the bottom one moves out from under, the top one will fall (always wished quake would do that)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@1637 d7cf8633-e32d-0410-b094-e92efae38249