This adds support for the beacon interval to be set on a per-band base.
This has the potential to reduce the amount of airtime used up for
sending beacon frames.

[Matthias Schiffer: fix up start/stop order and file permissions]

Separate wireless-related helper methods from the util module to a
new wireless module. This keeps them separated, as the amount of
wireless helpers increased in the past, justifying a separate module.

xt_CT was added to kmod-ipt-conntrack a while back. Update our
GLUON_SPECIALIZE_KERNEL rules accordingly.

When building xt_CT into the kernel, one of the symbols IP_NF_RAW and
IP6_NF_RAW must be enabled as well, even though there is no runtime
dependency when building as modules. The kernel grows by less than 1KB
even when both IP_NF_RAW and NETFILTER_XT_TARGET_CT are enabled, making
this change a (very slight) net win in both flash and RAM usage.

Closes #1974

Situation:
==========

$ ls -l /lib/gluon/domains/lindennord.json
lrwxrwxrwx    1 root     root            10 Jan  6 03:42 /lib/gluon/domains/lindennord.json -> dom17.json

Before:
=======

$ gluon-neighbour-info -d ::1 -p 1001 -r nodeinfo -c 1
{
   "node_id": "525400123456",
   "system": {
     "domain_code": "lindennord",
     "site_code": "ffh"
   },
...
}

After:
======

$ gluon-neighbour-info -d ::1 -p 1001 -r nodeinfo -c 1
{
   "node_id": "525400123456",
   "system": {
     "primary_domain_code": "dom17",
     "domain_code": "lindennord",
     "site_code": "ffh"
   },
...
}

Implemented using readlink() and basename() to the selected domain in
/lib/gluon/domains/${DOMAIN}.json.

As a partial fix to #496, do not touch the MAC address of the WAN
interface when using VXLANs (as only the MAC address of the VXLAN
interface matters to batman-adv).

config_ifname was renamed to setup_ifname in Gluon v2015.1.

On PoE-powered devices, we usually want to use WAN for the setup mode.
As all outdoor devices are PoE-powered, we can reuse this function. This
switches the setup mode interface for new installations / after config
reset on a few devices that were missing in this list before.

- Use util.find_phy()
- Stop foreach() as soon as the result is known

The 'preserve' flag can be used to mark a peer so it is not removed or
modified on upgrades. In addition, groups containing preserved peers are
not removed.

Fixes: #557

The netdev() lookup is confusing to use: whenever a interface does not
exist during boot (for example VLAN) or when the address is overridden
from board.json (which is not obvious at all), it will yield either no
address, or a different address than expected.

To avoid this confusion, using board.json-based interface() is
preferable. This converts all uses of netdev() to the corresponding
lan/wan lookups, except for the final fallback for eth0.

In most cases, board.json does not contain any MAC addresses; in this
case, the default MAC address of the underlying interface is to be used.

- Replace misnamed, closure-returning sysfs() to a reusable read() function
- Rename eth() to netdev(), pass full interface name
- Rename board() to interface()
- Split reuable get_netdev_addr() out of netdev()

gsub() returns the number of matches as its second return value. This
was unintendedly passed through by the util functions trim() and
node_id(). It can be presumed that this had no effect in practice, but
it can lead to surprising output when passing values to print() for
debugging.

Allows reconfigurtion of remote syslog from within site.conf.

Conflicts with the gluon-web-logging package as user made changes
will be overwritten, because this package will reconfigure the syslog
destination on every upgrade.

Resolves #1845

OpenWRT 19.07 enables urngd by default, so haveged is redundant.

OpenWRT 19.07 enables urngd by default, so haveged is redundant.

Use the value of the `name` site.conf field as label (it was
accidentally unused before).

Our site.conf currently doesn't define a specific order for the branch
entries. To avoid changing branch orders, sort entries by this label.

Fixes: #1961

Add a UCI setting gluon.mesh_batman_adv.hop_penalty

Example UCI commands:

    uci set gluon.mesh_batman_adv=mesh_batman_adv
    uci set gluon.mesh_batman_adv.hop_penalty=20
    uci commit

`/etc/config/gluon` config section:

    config mesh_batman_adv 'mesh_batman_adv'
    	option hop_penalty '20'

Fixes: #1942

Fixes commit 6692095f

Register to 'reset' event on form element and make call to 'update' function
delayed in 'data-update' handler to allow the form values to update beforehand.

When using a form's 'reset' button, form field visibility was not updated.
This could lead to situations where a checkbox had to be toggled again
twice to display the detail text inputs. (Example taken from private
wifi package)

Fixes #1959

Provide the number of OWE stations in addition to the number of all
connected wireless clients.

This allows a user to enable WPA3-Personal and WPA2-WPA3-MM for the
private WiFi in case it is supported by the platform.

This adds a helper method, which determines if the current platform
supports WPA3 or not.

WPA3 is supported if
 - the device is not in the featureset category "tiny"
 - the WiFi driver supports 802.11w management frame protection