treewide: consolidate "From " line removal

Aside from our prior import bugs (fixed in a0c07cba0e5d8b6a
(mda: drop leading "From " lines again, 2016-06-26)), we'll
always have to be dealing with mutt piping messages to us and
`git format-patch' output.  So just share the regexp so we
can use it everywhere.

In may be desirable to allow importing messages with a leading
"From " line for FUSE, even.

Additionally, some instances of this regexp needlessly added
optional `\r?' (CR) checks ahead of the `\n' (LF) element; but
they're pointless anyways since [^\n]* is enough to exclude all
non-LF bytes.

0 files changed, 0 insertions, 0 deletions