Drop now-unused (by C) callee code.

This will break Objective-C, although I've tried to indicate with TODO marks where and what I think might be done to use the new API.

Of course, since Objective-C doesn't have any tests yet, would an empiricist really call it broken?
Trivial: whitespace.
Add missing #include guards.
Use OwningPtr rather than pointer-and-delete.