send-email: don't use Mail::Address, even if available

send-email: don't use Mail::Address, even if available

Using Mail::Address made sense when we didn't have a proper parser. We
now have a reasonable address parser, and using Mail::Address
_if available_ causes much more trouble than it gives benefits:

* Developers typically test one version, not both.

* Users may not be aware that installing Mail::Address will change the
  behavior. They may complain about the behavior in one case without
  knowing that Mail::Address is involved.

* Having this optional Mail::Address makes it tempting to anwser "please
  install Mail::Address" to users instead of fixing our own code. We've
  reached the stage where bugs in our parser should be fixed, not worked
  around.

Signed-off-by: Matthieu Moy <git@matthieu-moy.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>