Began transition to zipper-polymorphic interface, using typeclasses to allow for polymorphic references. Chased down a tricky bug in the process, where I accidentally borked the duplicate method for the comonad instance for Z2 (I had rewritten it to use zipU/zipD instead of the correct zipL/zipR, in the duplicateHorizontal piece.).
Renamed to Generic from Class. Added 'goto' function which is equivalent to go . at.