Remove deprecated OpenGL 1.1 Fixed Function Pipeline Renderer

[Stan]

While still functionnal the Fixed Function Pipeline code is old, OpenGL 1.1. is very old (1997!) too, it is slow, it’s not very well tested, as it’s not possible to enable it through the options (albeit the hardware detection can force it), and while it works, it will crash if any of the new features e.g. postprocessing are enabled. And the last one is the fact it was marked as deprecated almost 7 years ago: in r13156. The only argument “for” that I can find is that some users (62/10000+) use it.