Refactor Compositor;

- Move #view from Compositor up into Buffer; this way, Buffer can be responsible for
which content should be rendered.
- Inject the interface and buffer attributes into Compositor instead of a name; moving towards dependency injection with this approach.
- Add #cursor to Focus so we can easily retrieve the escape sequence for the cursor for the focussed interface.
- Remove options from Output, refactor to simplify. Temporarily comment out tests.
Add Sentence class to construct Oxford English lists;

['This', 'That', 'The Other'] becomes "This, That and The Other".
Delegate Vedeu.height and Vedeu.width to respective Terminal methods.
Add require to fix tests.