- bumped minimum supported OpenGL version to 1.4. The engine was already using several 1.3 and 1.4 features which would have caused problems on 1.2.
- removed gl_vid_compatibility. With the bump to 1.4 no hardware requiring this flag is supported anymore.
- disabled 16 bit framebuffers for the same reason. As a conseqence all code for rendering without stencil could also be removed.