Split Renderer and desired openGL Version

[MeFisto94]

Currently our AppSettings are very static leading to code as you can see in #1252
We need switch statements and other tricks to extract the version number out of the string.

I'll first want to discuss this with you, as I might be overlooking things, but:
Can we say Renderer = LWJGL3, OPENGL_MAJ = 3, OPENGL_MIN = 2 for LWJGL3 OpenGL 3.2?

I know that JOGL falls out of that row, as they don't support a specific version but have FORWARD_[...] etc, but those could then just ignore the OpenGL Version specified and be seperated Renderers as has been already.

Technically every Rendering Backend should want an OpenGL Version at some point, and it would be much better if we had two dedicated integers for it, so we don't have that ugly parsing and also don't have to add it when new versions emerge.