Transparent sorting: added maxdist and array size cvars which can be tweaked to incre...

Transparent sorting: added maxdist and array size cvars which can be tweaked to increase performance (can give up to 10-20% with no quality loss on scenes with large amount of blended surfaces). Added "dpnortlight" shader keyword which disables full rtlight rendering on a surface, useful with grass which (when blended) can cause deadly speed loss.

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@11090 d7cf8633-e32d-0410-b094-e92efae38249
::stable-branch::merge=ec581e708c6874f1e1fa64343421683fd16f8609