Add parsing of elm aliases to git-send-email

elm stores a text file version of the aliases that is
<alias> = <comment> = <email address>

This adds the parsing of this file to git-send-email

Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-send-email.txt

@@ -262,7 +262,7 @@ sendemail.aliasesfile::
 
 sendemail.aliasfiletype::
 	Format of the file(s) specified in sendemail.aliasesfile. Must be
-	one of 'mutt', 'mailrc', 'pine', or 'gnus'.
+	one of 'mutt', 'mailrc', 'pine', 'elm', or 'gnus'.
 
 sendemail.multiedit::
 	If true (default), a single editor instance will be spawned to edit

git-send-email.perl

@@ -418,6 +418,14 @@ sub split_addrs {
 			$x =~ /^(\S+)$f\t\(?([^\t]+?)\)?(:?$f){0,2}$/ or next;
 			$aliases{$1} = [ split_addrs($2) ];
 		}},
+	elm => sub  { my $fh = shift;
+		      while (<$fh>) {
+			  if (/^(\S+)\s+=\s+[^=]+=\s(\S+)/) {
+			      my ($alias, $addr) = ($1, $2);
+			       $aliases{$alias} = [ split_addrs($addr) ];
+			  }
+		      } },
+
 	gnus => sub { my $fh = shift; while (<$fh>) {
 		if (/\(define-mail-alias\s+"(\S+?)"\s+"(\S+?)"\)/) {
 			$aliases{$1} = [ $2 ];