mesh: Add mesh peering manager

mesh: Add mesh peering manager

The mesh peering manager establishes and maintains links among
mesh peers, tracking each peer link via a finite state machine.

This implementation supports open mesh peerings.

[assorted fixes from Yu Niiro <yu.niiro@gmail.com>]
[more fixes from Masashi Honma <masashi.honma@gmail.com>]
Signed-off-by: Javier Lopez <jlopex@gmail.com>
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: Ashok Nagarajan <ashok.dragon@gmail.com>
Signed-off-by: Jason Mobarak <x@jason.mobarak.name>
Signed-hostap: Bob Copeland <me@bobcopeland.com>