Patch to bring if_bridge up to date more

[Scott Ullrich]

Hi!

I have a patch to bring if_bridge up to date a bit more.

New features include:

* better handling of fragmented packets
* newer spanning tree support
* txcsum fixes
* monitor mode (multiplex bpf)
* spanports
Get the patch from:
  http://leaf.dragonflybsd.org/~geekgod/if_bridge/dfbsd.diff
Patch originally adapted from a version done by Andrew Thompson
With-help-from: @corecode, @sephe, thompsa at xxxxxxxxxxx
Thanks to the work done prior in ifconfig, this patch required no
changes. :)
If no objections, I would like to commit by Friday 30, 2006.

Scott