cd audio now tied to sound system

cd audio now tied to sound system
sound system now tied to video system because DirectSound needs a window to work at all (thank you Windows for another useless obstacle)
sound system can now restart (snd_restart command)
vid_stencil cvar removed (now tied to 32bit color)
vid_bitsperpixel now defaults to 32
r_shadow_shadows cvar added (default 1) for stencil shadows on dlights (since vid_stencil is gone)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@3548 d7cf8633-e32d-0410-b094-e92efae38249