This reverts a5c484cb. The test included
in a5c484cb is wrong and contains a typo that leads to incorrect
assumptions. The Dungeon Keeper 2 crash that was the reason for patch
a5c484cb is fixed properly by the previous patch.

Introducing rendertarget views will (eventually) allow rendering to 3D
textures and buffers.

Like "draw_binding".

Like volumes. We can do this now because we no longer have standalone
surfaces.

The texture always has the only reference to its subresources. This also means
we never have to set the container to NULL.