Begin work on the new rendering system.
Work on converting over to the new rendering system.

This is now mostly finished, just testing to go.
Fix a bug where the offset was not being sent to the renderer correctly.
Cleanup dead code.
Add an argument to Renderer::Begin() so implementations can easily access the server.
Fix a bug where Renderer::Begin() and Renderer::End() are not being called.

This also fixes a bug where the position of z-indexed elements were not being rendered in the correct positions.