Mesh fixes and improvements

[Javier Cardona]

[Resent with proper patch numbering...]

This series includes some fixes, testing aids and improvements to the mesh
stack.  It is important to note that the patch
"Use-3-address-format-for-mesh-broadcast-frames" breaks compatibility with
previous versions.  This is unavoidable and will keep happening as new versions
of the 802.11s drafts are produced.

Also, I'm not sure if "Simulate-transmission-losses-on-plinks-to-..." should be
merged upstream, but we find it really useful to test mesh configurations.
Please comment if you have different opinions on its adequacy or
implementation.

Cheers,


Javier