Replace almost all texture uses with calls to the new system.
Add some anistropic filtering to terrain textures.
Let Atlas load terrain texture previews partly-asynchronously by
polling.
Fix inefficient texture colour determination for minimap.
Remove unused global g_TerrainModified.
Change GUI texcoord computation to be less efficient but to cope with
dynamic texture changes.
Fix GUI renderer effects leaving bogus colour state.
This was SVN commit r8099.
- ogl_tex_bind now supports multitexturing (avoids need to get id and
then bind manually)
- provide nicer API for querying texture properties (no longer one big
getter). improved GUI determination of texture alpha.
- renderer: another see-if-texture-has-alpha and fixed alpha map code
(wasn't checking if all are same size. only worked because the first map
was larger than the rest
This was SVN commit r2647.
