rebinds them to something else.  Fix debug mode crash when the user
typos a menu name.  Add menus for pageup and pagedown bindings and make
rebinding up and down actually do up and down and not page up and page down.


git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@4221 35c25a1d-7b9e-4130-9fde-d3aeb78583b8