Add an argument to notmuch-mua-mail

Add an argument to notmuch-mua-mail

From the emacs changelog:

  ** `compose-mail' now accepts an optional 8th arg, RETURN-ACTION, and
  passes it to the mail user agent function.  This argument specifies an
  action for returning to the caller after finishing with the mail.
  This is currently used by Rmail to delete a mail window.

Under Emacs 24, notmuch breaks when this argument is passed to it by a
function in another part of Emacs.  One example of a functon that does
this is report-emacs-bug -- so notmuch users cannot file emacs bug
reports!

This patch also adds a &rest argument to the arg-list of this function,
to future-proof against such changes.  This is adapted from the approach
taken by message-mail, a similar function built into emacs.

This patch was originally submitted by richardmurri@gmail.com on Aug. 1:
id:"877h6x6oor.fsf@veracitynetworks.com"