DemoGame can define a Block asset type

[temportalflux]

• Should "Block" be named something else? Its really just an object in the world that doesn't move, and not all blocks are rendered as cubes or have cube collision
• How can demo game hook into the engine to tell it about new asset types
• Block asset which defines asset references to:
  • model file (verticies which contain pos, texcoord, normal)
  • texture assets per face model asset will need to define these faces in terms of vertex sets
  • texture sampler asset
• A block registry is needed in order to compile metadata about a Block asset like
  • which atlas sampler should be used when it is rendered
  • what are the uv offsets in the atlas for a given face