Fix incorrect logic for flaremap selection in R_ProjectSprite()
Server: Removed unused Objlink blockmaps

The Objlink blockmaps are not needed on server side. These blockmaps
are used by the client's map renderer when projecting the mobjs and
lumobjs of the current map.
Server: Remove various material/texture logics needed only by the client
GL Texture Manager|Refactor: Numerous cleanup refactorings