Confusion of WAN an LAN, this line is for mesh-on-lan

These devices are identical to the TL-WR941 v4 & v5, so we don't need to
test them explicitly.

usign has pulled in new dependencies, and OpenWrt doesn't like the command
`make tools/prepare` in a clean build.

Fixes #540

This will fix the early preparation happening much too often and also fixes
early preparation after `make clean`.

Update kernel to 3.18.23

This broke due to the Makefile changes for building the module repo.

Update site.rst

The Freifunk Münsterland firmware was formerly known as Freifunk Münster firmware - while the URL hasn't changed. In future, there will probably be subdomains with their own files, but for now this is state of the project.

doc: remove duplicate article in getting_started.rst

Generate opkg repo for kernel modules

`make modules` will generate a opkg repository containing kernel modules
matching the kernel of the Gluon images.

We'll soon have other output besides the images, having a single directory
for all output makes sense.

The upstream builds always use LINUX_RELEASE=1. By setting it to 2 we
ensure that our modules are always preferred as long as our kernel version
is at least as high as the upstream one.

As the Gluon kernel won't be compatible with the OpenWrt upstream anymore,
we don't need the vermagic hack anymore.

doc: remove double opening next_node line in site.conf example

I guess this is some copy and paste mistake which makes the example an
invalid site.conf. In my case merging the changes of the example into
our actual site.conf lead to an error because this line was merged to.

Fixes #376

Fixes #534

Fixes #487

gluon-status-page: new status page

gluon-mesh-batman-adv-core/gluon-luci-portconfig: fix configuration of br-client ifname with multiple interfaces in lan_ifname

There are a few devices on which lan_ifname contains multiple interface
names separated by spaces.

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

gluon-radio-config contained only a single file. The code has been adjusted
to allow creating a Gluon configuration without WLAN support by removing
the wifi24 and wifi5 sections from site.conf.