[B.A.T.M.A.N.] switch routing algorithm at runtime (v2)

Hi,

next round for the selectable routing algorithm patches. The major change which comes with this patchset is the module parameter that allows to set the routing algorithm. This setting only affects batX interfaces created after the change has been made. The list of available routing algorithms moved to the batman-adv debugfs root directory, so that it is visible even before the first batX interface has been created. The sysfs entry still shows the configured routing algorithm but does not allow to change it.

Big kudos to Sven for helping me out with the compat macros.

Cheers, Marek