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.

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

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.

Fixes commit 6692095f

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

Remove a lot of redundant code by switching to a match table listing
the targets and boards for each candidate for the primary MAC interface.

In addition, we add some flexiblity by allow to switch out the sysfs file
data source for the MAC address.

Allow wildcard matches on all subtargets of a target, or a full wildcard
always returning true when no arguments are passed.

Specification:
- MediaTek MT7620A (580 Mhz)
- 64 MB of RAM
- 8 MB of FLASH
- 2T2R 2.4 GHz and 1T1R 5 GHz
- 5x 10/100 Mbps Ethernet
- 2x external, non-detachable antennas
- UART (J1) header on PCB (115200 8n1)
- 8x LED (GPIO-controlled*), 2x button, power input switch
- 1 x USB 2.0 port

This commit accounts for the target renaming which was done in upstream
commit 7407e723991 ("ipqx0xx: add Generic subtarget")

This commit accounts for the target renaming which was done in upstream
commit 7407e723991 ("ipqx0xx: add Generic subtarget")

mac_to_ip() calculates an ipv6 address from a mac address according to
RFC 4291. For wireguard we have to use specially crafted addresses that
must be unique. This allows calculating such unique mac-based addresses
by allowing to optionally specifying the bytes to be inserted into the
address.

This is a fix for the broken ingress traffic-shaping in gluon v2018.2.2
and possibly earlier.

For ingress traffic shaping the kernel option NET_ACT_POLICE is needed.
Before this patch there was no dependency to this. Neither in
gluon_core, gluon-mesh-vpn-core nor in the package.

This patch adds this dependency.

[Matthias Schiffer: move dependency from GLUON_CORE to gluon-mesh-vpn-core]

Fixes #1790

Fixes #1771