Attempt to implement Q4engine style bob-rolling (the view discretely rolls to the...

Attempt to implement Q4engine style bob-rolling (the view discretely rolls to the sides as you walk). Things to do before it is ready:

TODO 1: Make it work around the center rather than the left side
TODO 2: Don't bob roll when not touching the ground
TODO 3: Write cvars in darkplaces.txt, set better defaults and possibly disable by default once the first TODOs are ready.

From: MirceaKitsune <sonichedgehog_hyperblast00@yahoo.com>

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@10277 d7cf8633-e32d-0410-b094-e92efae38249
::stable-branch::merge=e7307bf7059d55da536603a7e41dbefb5eb3a2b4