docs: releases/v2015.2: add ubiquiti airgateway

On the status page statistics section counters for transmitted and received traffic were mixed up. Transmitted traffic was shown as received while received traffic was shown as being transmitted.

Fixes #586

OpenSSL: Added source/old to PKG_SOURCE_URL

OpenSSL moves old versions of the library from http://www.openssl.org/source/
to http://www.openssl.org/source/old/1.0.2/ breaking the old links. That
behavior breaks the OpenWRT-build every time OpenSSL releases a new version.

This patch adds http://www.openssl.org/source/old/1.0.2/ to the PKG_SOURCE_URL
of OpenSSL to avoid breaking the build whenever OpenSSL releases a new
version.

Fixes #579

docs: add v2015.2 release notes

gluon-luci-private-wifi: fix typo in code file and regenerate translation files (correctly this time)

targets/ar71xx-generic: add WD MyNet N600/N750

docs: add link to tecff/site-ffa (Altdorf, Landshut & Umgebung)

Signed-off-by: Felix Kaechele <felix@kaechele.ca>

-spelling

Also
* create list of newly supported devices since v2015.1.2 in the v2015.2 release notes
* update information on docs/user/x86
* fix a comment in targets/ar71xx-generic/profiles.mk

gluon-mesh-batman-adv-core: keep disabled state even when the mesh interface section name is changed

Fix typo in LICENSE

This patch is already included in the current OpenWrt CC branch.
Cherry-pick for now as we're very close to the Gluon 2015.2 release.

In line 2: indiviual -> individual

The trunk version of mac80211 doesn't need these dependencies anymore as
they are compiled into the kernel.

While this didn't cause any issues for Gluon as we always build the kernel
with all modules, this fix makes the patch work on a plain OpenWrt CC as
well.

gluon-mesh-batman-adv-core: keep disabled state even when the mesh interface section name is changed

Is makes sense to always look for both ibss_radio* and mesh_radio* sections
to determine if the meshing should be enabled when regenerating these
sections. Doing this, the disabled state will survive updates changing the
section name (either updating from pre-2015.2 while keeping IBSS, or
changing from IBSS to 11s or vice-versa).

If both ibss_radio* and mesh_radio* sections exist, the disabled state will
be kept correctly for each section, the behaviour is changed only when
creating a section that didn't exist before.

Fixes #549

PKG_FILE_DEPENDS caused the whole site repo to be hashed to determine if
gluon-site needed rebuilding. While this is normally no problem,
alternative build setups sometimes put the Gluon repo inside the site repo,
causing long build times and parallel build failures.

docs: improve user/getting_started, some minor fixes in user/site

in a layer 2 mesh network, multicast pings cause a lot of traffic in the
network, significantly increasing the 'backgroudn noise' (= Grundrauschen)
and stressing nodes in the network.

this commit blacklists all icmpv4 multicast traffic as well as multicast
icmpv6 echo-requests and node iformation queries. as no application
depending on these types of multicast traffic is known, blacklisting is safe.