Commit the remainder of Max's dma work (with minor modifications).

Commit the remainder of Max's dma work (with minor modifications).
See Max mail on kernel@ [1] for further details.

* Support of .forward files (Note: dma is now setuid root)
* Send multiple mails at once
* Fix some style(9) issues (mostly return())

Some style(9) issues are still in the code.  I take care if I have some
spare time :)  Please test!

Submitted-by: Max Lindner <gisanka@gmail.com>
Sponsored-by: Google Summer of Code 2008
[1] http://leaf.dragonflybsd.org/mailarchive/kernel/2008-08/msg00045.html