Don't bind *MENU-MAP*, pass keymap as an argument

This also removes the need to define bindings for navigating and
aborting. I kept the "j" and "k" bindings in place, because they don't
exist by default.
Merge pull request #10 from jorams/keymap-as-argument

Pass keymaps as an argument to SELECT-FROM-MENU, instead of binding *MENU-MAP*