Signed-off-by: David Bauer <mail@david-bauer.net>

A microsecond is commonly abbreviated as µs. This prevents confusions
between micro- (µs) and milliseconds (ms).

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.

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

(cherry picked from commit 7f3a3042)

This device has broken Ethernet on both ports.

Remove support for those devices. for now, as there was no feedback from
the original author.

Closes #1943

v2 is available on the market, but apparently has no upstream support, yet:
https://forum.openwrt.org/t/v2-of-cudy-wr1000/56965

This allows to define a list of packages, which are only installed
for a specific device-class.

(cherry picked from commit 447595f0)

fixes #1935
found by @lrnzo

(cherry picked from commit 63ebeb25)

- vendor name should not be part of model name
- there's no other version, hence mentioning the version is superfluous

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

TP-Link TL-WR902AC v3 is a pocket-size dual-band (AC750) router
based on MediaTek MT7628N + MT7650E.

Specification:
- MediaTek MT7628N/N (580 Mhz)
- 64 MB of RAM
- 8 MB of FLASH
- 2T2R 2.4 GHz and 1T1R 5 GHz
- 1x 10/100 Mbps Ethernet