Add support for add/remove newline before and after ObjC @interface/@implementation lines.
Improve typing of chunks in ObjC @interface/@implementation lines.
Admittedly, ObjC being largely whitespace agnostic, there could have been many more options
(i.e. nl before/after class colon, category name, superclass, protocol list) but this is the
option I needed, so it's the one I built.