[MERGE] Add mail-mode GNU Emacs mail package as a mail_client option.

[Ian Clatworthy]

Xavier Maillard wrote:
> Hi,
> 
> This is the third try.

Thanks.

You should include an item in NEWS crediting yourself.

Also, there are a few things that need fixing to meet PEP-8. I'm
mentioning them below so you're aware of them when submitting other patches.

> +class EmacsMailMode (ExternalMailClient):

No space before ( here.

> +    """Call emacsclient in mail-mode. This only work for emacs >= 22.1"""

Docstring should have first sentence on 1st line, blank line, then
remaining info.

> +    def _get_compose_commandline (self, to, subject, attach_path):

No space before ( here.

> +        commandline = ["--eval"]
> +        #Ensure we can at least have an empty mail-mode buffer

Space after # preferred here.

> +        mmform = "(mail nil %s %s)" %(_to ,_subject)

Space after % here.

> +        self.assertEqual(['--eval', '(mail nil nil nil)',
> +                          '(mail-text)' , '(newline)',

Space before comma not wanted here.

I'll make these tweaks and merge.

Ian C.