Add 3D support

[AntiSC2]

Right now only 2D is supported but I want 3D to be possible too. The first steps to adding basic 3D support should not actually be that hard. The first step is just creating a camera that has a perspective view and then creating a mesh class or something similiar to generate a bit of 3D geometry. All entities already support 3D positioning.

[AntiSC2]

Current task list:

• [x] 3D camera

• [x] Mesh loading

• [x] 3D renderer

• [x] 3D shaders

• [x] Point lights

• [ ] Directional light