Redesigned Scene Elements + Added Overlay Renderer, Triangle Mesh (WIP)

The hexes might be rendered using the triangle mesh instead, storing the
information in faces and vertices instead. This allows triangle strips.
The Mesh and Face/Vertex/Edge classes might also be moved to MFUL, but
I'm unsure. Also, the efficiency of V/E/F objects vs arrays is uncertain
at the moment. Also, VBOs need to be considered.