[RFC] Updated plane handling

[Jesse Barnes]

This set refactors thing a bit more and tries to somewhat unify
presentation of primary and sprite surfaces.  I broke something though
because terminal-in-a-sprite no longer works, but I think the
refactoring is interesting to look at anyway.

Any thoughts?  Kristian, you mentioned something about a buffer
reference structure; how would that fit in here?  Would we track a list
of them in the output?

Thanks,
Jesse