Add tests for formatting codes

Not that they work yet, of course :) .
Write up basic formatting code support.

Update tests a bit too :) .
Specially handle L<>, write tests for them.

L<> is the only formatting code that requires special handling from the
parser.
Start formatting code support

Stuff is *horribly* broken though, do not use.
Fix said bug.

Somehow.

I don't even know.