send-email: be more lenient and just catch obvious mistakes.

send-email: be more lenient and just catch obvious mistakes.

This cleans up the pattern matching subroutine by introducing
two variables to hold regexp to approximately match local-part
and domain in the e-mail address.  It is meant to catch obvious
mistakes with a cheap check.

The patch also moves "scalar" to force Email::Valid->address()
to work in !wantarray environment to extract_valid_address;
earlier it was in the caller of the subroutine, which was way
too error prone.

Signed-off-by: Junio C Hamano <junkio@cox.net>