Allow specifying no, one, or multiple hook names

Allow @hacks.use('my.module:deeply.buried.hack')

@hacks.before and @hacks.after wrappers

Fixed package building

__on_enter__ and __on_exit__ hooks, nicer README

Add __on_enter__ and __on_exit__ hooks for hacks

Rewrite with mutants

Helpers for stealing frameinfo of hack callers

Packaging fixes and a new test