This is a big shift in the formatter API's. It simplifies the
responsibilities of the implementers so that pretty much all they
have to do it implement an iterator. Everything else will be
automatically derived from that. (Or, at least, that's the hope.)
This commit pulls the formatter out of the text buffer and
puts it in the editor instead. However, there is a lot of
commented code utlizing the buffer and formatter that still
needs to be updated.
In short, the editor is pretty non-functional in this commit.
