[Matthias Schiffer: move to proto_gluon_bat0_setup() and default to BATMAN_IV]

For simplicity, we don't use different MTUs for compat 14 and 15 anymore,
there's no harm in using 1532 for batman-adv-legacy as well.

These values have been in use in gluon-core for some time, the validators
need to be moved as well.

gluon-client-bridge, gluon-mesh-batman-adv-core: switch roles of br-client and local-node interfaces

MAC and IP addresses are switched. This makes the gluon-client-bridge
package more useful for different routing protocols that don't need a
unique address on the client bridge.

As a side effect, gluon-radvd is now using the next-node address, which had
been considered before, but was dismissed to avoid having gluon-radvd
depend on gluon-next-node and gluon-mesh-batman-adv. This will be useful
for announcing default routes via gluon-radvd.

One downside is that this introduces a minor dependency on batman-adv in
gluon-respondd: the hotplug script that checked for the client interface
before will now check for local-node. This doesn't really matter: for mesh
protocols without a local-node interface, the check will do nothing (which
makes sense, as there is no interface to bind to for mesh-wide respondd).

This package provides br-client and sets up a wireless AP interface for
clients.

Fixes #401

Split basic radio configuration from gluon-mesh-batman-adv as this will
be required for virtually any wireless mesh protocol.

This package takes care of setting:

  - wireless channel,
  - htmode and
  - regulatory domain

gluon-mesh-batman-adv-core depends on this package.

This is a site.conf-breaking change in regard to the wireless config.
Make sure to read http://gluon.readthedocs.org/en/latest/user/site.html
and update your site.conf accordingly!

Support for 802.11s mesh interfaces has been added. Gluon now supports
three interface types: ap, ibss and mesh. All of them are now optional
and may be configured independently in site.conf.

A sample site.conf may look like this:

    wifi24 = {
            channel = 1,
            htmode = 'HT40+',
            ap = {
                    ssid = 'luebeck.freifunk.net',
            },
            ibss = {
                    ssid = '02:d1:11:37:fc:38',
                    bssid = '02:d1:11:37:fc:38',
                    mcast_rate = 12000,
            },
            mesh = {
                    id = 'ffhl-mesh',
                    mcast_rate = 12000,
            },
    },

This adds mesh_on_lan functionality.

A new optional site.conf option, mesh_on_lan, has been added. If set to
'true', all LAN ports will be used for meshing instead of being part of
the client bridge.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>