emacs: use "C-h" for backspace

like you use in terminals. less of a stretch than the backspace key,
especially in god mode.

globally binding C-h to backward-delete-char covers normal use. special
bindings also had to be done for in isearch and ido. it's possible that
i'll discover some other modes which also need something special done.

help can still be accessed with F1.
emacs: make backspace just delete during isearch

during isearch backspace will cycle backwards through results until it
reaches the first, before it starts to delete the search text. make it
just delete the search text instead.