Organize termbox file

Simply moving around functions to more appropriate, findable locations.
Add soda theme submodule
Implement soda theme tabs
Merge pull request #231 from vially/qml-tabs

* Rebased and squashed.
Update visible region with insert/erase delta

Adding a callback to the current views buffer allows the visible region
to update based on the delta of inserted/erased characters. This
prevents characters disappearing at the bottom right of the visible
region when typing.