worked around curve collision problems by doing special sort-of-axial edge planes...

worked around curve collision problems by doing special sort-of-axial edge planes on triangle collisions (ultimately the collision routine needs to do edge/edge collisions somehow to make this unnecessary)
now snaps triangle mesh vertices to 1/32 of a unit precision to keep the plane calculations a little more accurate (note: this is done at collision time), although this doesn't seem to be necessary
collision nudge values are now configurable via cvars (collision_ cvars, warning: things tend to break if startnudge != endnudge, and enternudge should be the same as leavenudge)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@3985 d7cf8633-e32d-0410-b094-e92efae38249