treat .git/*_EDITMSG the same

COMMIT_EDITMSG, PULLREQ_EDITMSG, etc
PF3 uses setlocal, not set, to turn off numbers for the current buffer

yay localization! :)
setup PF5 to toggle spell checking on and off
nit! whitespace
nit! trim some of the attic out
turn on spell-checking, off line numbers, for git commit buffers