Cleaning up platform specific OpenGL includes.
Minor change to texture loader to return the bytes of the texture so that they can be freed up properly later.
Minor fix to freeing allocated texture handles, and changed texture handle to be GLuint.
+ MeshAsset, + Models (basic)
Converted mesh into a MeshAsset that can now be shared between multiple GameObjects. It has its own (basic loader)
MeshAssets embed the previously added TextureAssets inside them so that those can be shared between multiple MeshAssets as well.
Added a couple of basic models for squares and cubes.