class Element is completely gone.
(The files are still there but no longer compiled in. Will delete later)
Broken still:
- support for vertical flip
- the editor
- culling
This takes out the last of the RenderObject mutables.
This also fixes the long-standing editor bug that map tiles
that are once moved to parallax layers and then back to a
normal layer keep their scroll factor until the tile is deleted
or the map saved and reloaded.