Gun model leaning effect when looking around (eg. the faster you look up the more...

Gun model leaning effect when looking around (eg. the faster you look up the more your weapon model lowers itself). Things that need to be done before this is ready:

TODO 1: Fix bug where model does a 360* turn when YAW jumps around the 0 - 360 rotation border.
TODO 2: Implement limits (weapon model must not lean past a certain limit)
TODO 3: Cvar everything once the first TODOs are ready.

Sister project (can be separate and done some other time): Push / pull the weapon model based on the direction you are running in.

From: MirceaKitsune <sonichedgehog_hyperblast00@yahoo.com>

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@10123 d7cf8633-e32d-0410-b094-e92efae38249
::stable-branch::merge=b47413e8cd93060c1a18827c08358e46ad9e9ec4