v0.12.0-beta - now fully OpenGL rendered

There's now a somewhat new API for the graphics due to the difference in working with the CPU and the GPU, and it's not 100% finalized. Sprite rendering needs to be better optimized (likely can be done on a single draw call per material and shader program), "framebuffers as sprites" need to be added for the editor to work, there are even new bugs, etc., but I thought this current state already warrants a release.