Fix bugs with unloading of cachepic skinframes in QC menus - the reloading was broken...

Fix bugs with unloading of cachepic skinframes in QC menus - the reloading was broken in some weird way that made it white (it wasn't reusing the skinframe).

Simplify Draw_CachePic behaviors with regards to NewPic and textureflags (mismatch now causes texture reload rather than having multiple with the same name in memory).

Improved reloading of unloaded pics by reusing the existing skinframe, so it can not produce duplicates.

Make Draw_NewPic clear the pic->autoload flag, this is a behavior change in VM_CL_ReadPicture.

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@12407 d7cf8633-e32d-0410-b094-e92efae38249