The LeiInput backend now allows p2q to work like any other
command which reads .eml, .patch, mbox*, Maildir, IMAP, and NNTP
input. Running "git format-patch --stdout -1 $COMMIT" remains
supported.
This is intended to allow lower memory use while parsing
"git log --pretty=mboxrd -p" output. Previously, the entire
output of "git log" would be slurped into memory at once.
The intended use is to allow easy(-ish :P) searching for
unapplied patches as documented in the new example in the
manpage.