git-send-email: add a new sendemail.to configuration variable

Some projects prefer to receive patches via a given email address.
In these cases, it's handy to configure that address once.

Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/git-send-email.perl b/git-send-email.perl
index 62e1429..96051bc 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -191,6 +191,7 @@
     "smtpserverport" => \$smtp_server_port,
     "smtpuser" => \$smtp_authuser,
     "smtppass" => \$smtp_authpass,
+    "to" => \@to,
     "cccmd" => \$cc_cmd,
     "aliasfiletype" => \$aliasfiletype,
     "bcc" => \@bcclist,