Allows to remove some redundant UCI lookups.

Some files have received some additional refactoring.

In particular, this affects users of gluon.util.iterate_radios.

gluon-core: gluon.util: pass UCI cursor as argument to iterate_radios() instead of using local context

We also make use of the boolean support of simple-uci to make scripts
clearer.

Some drivers (mt76) don't support arbitrary MAC addresses. Use the
addresses provided by the driver (avoiding the primary address) by default,
but fall back to our has-based scheme when the driver doesn't provide
(enough) addresses.

Lua's tables are 1-based, so we must decrement the index by 1 to get the
desired MAC addresses. By not doing this, the second IBSS interface would
get the address with index 8, but only indices 0..7 are available.

Fixes: c73a12e0

While ath9k/ath10k devices can supprt VIFs with any combination of MAC addresses, there are also adapters which have a hardware MAC filter which only allows a few bits to differ. This commit changes the addresses of all VIFs to ony differ in the last 3 bits, which is required to support many Ralink/Mediatek based WLAN adapters.

Technically, the new addresses are generated by calculating an MD5 hash of the primary MAC address and using a part of this hash as a prefix for the MAC addresses.

The addresses (BSSIDs) of the AP VIFs are also reused for the LAN and WAN interfaces in mesh-on-LAN/WAN mode to reduce the number of needed addresses, and thus reduce the chance of collisions. This is not a problem as the MAC addresses of the AP VIFs are never used except as BSSID, and thus not seen by routing protocols like batman-adv.

Fixes #648

[Matthias Schiffer: rewrote commit message]

Avoid commiting configs inbetween to decrease number of flash writes.

Fixes #714.

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