- removed some obsolete and useless GL calls.
- allow reallocation of light buffer if more lights are needed.
- added a light preprocessing pass to the renderer so that a non-persistent buffer can be used with minimal mapping/unmapping. This only gets used if necessary because it adds some overhead to the renderer.
- screwed by the editor's autocompletion... (wrong GL flag was used...)
- lowered requirements of GL 2.x to OpenGL 3.3.

There was one issue preventing the previous 2.0 betas from running under GL 3.x: The lack of persistently mapped buffers.
For the dynamic light buffer today's changes take care of that problem.
For the vertex buffer there is no good workaround but we can use immediate mode render calls instead which have been reinstated.

To handle the current setup, the engine first tries to get a core profile context and checks for presence of GL 4.4 or the GL_ARB_buffer_storage extension.
If this fails the context is deleted again and a compatibility context retrieved which is then used for 'old style' rendering which does work on older GL versions.

This new version does not support GL 3.2 or lower, meaning that Intel GMA 3000 or lower is not supported. The reason for this is that the engine uses a few GL 3.3 features which are not present in the latest Intel driver.
In general the Intel GMA 3000 is far too weak, though, to run the demanding shader of GZDoom 2.x, so this is no real loss. Performance would be far from satisfying.

A command line option '-gl3' exists to force the fallback render path. On my Geforce 550Ti there's approx. 10% performance loss on this path.