Stereoscopic 3D support

See ?AndreasEhliar's page on the subject: http://www.lysator.liu.se/~ehliar/3d/ .

Implementation of Quad-Buffer Stereo for radeon and r200.

Latest post: 20041019 -- http://marc.theaimsgroup.com/?l=mesa3d-dev&m=109817901921774

Older posts: http://sourceforge.net/mailarchive/forum.php?thread_id=4834128&forum_id=5154 or http://marc.theaimsgroup.com/?l=mesa3d-dev&m=108610583529027