Before, android_version.h got changed at every new commit. Now, we
only change it with new minetest releases. Analogous to how cmake
does it,  we add an android_version_githash.h file that communicates
the git hash to C++ code.

Also, unify VERS_MAJOR, VERS_MINOR and VERS_PATCH variable
calculation inside the whole makefile.

-> Remove the SendableMediaAnnouncement struct
-> Forge the packet directly in the m_media loop, spare one loop and the construction of a vector
-> Use preincrement to spare iterator copies

Before, our libiconv build was a joke. We first called configure for our own build host system,
then called make, before we executed a Android.mk script we provided as patch. The first "native make"
always failed, and the LIBICONV_LIB file setting in our Makefile didn't match the built one,
resulting in an always-rebuild of iconv.

This commit cleans up this total mess, removes the double-build, and the Android.mk, and properly calls
./configure with the according target platform, and uses a built toolchain.

As we have to deal with the android bug "NDK: Support for prebuild libs with full sonames"
https://code.google.com/p/android/issues/detail?id=55868
as the 2013 patch
https://lists.gnu.org/archive/html/libtool-patches/2013-06/msg00002.html
by Google's David Turner wasn't inside the 2011 libtool, we pass -avoid-version to
libtool.

Thanks to the proper build, wide_to_utf8 works for android now, removing us of the need to disable it.

Thanks @Zeno-

Since 03e0dd33 the calls didn't return an output count
for the recipes.

Also add static identifier as upstream did

always evaluate to true.

This was needed due to the TileDef serialisation changes. Originally it has been planned
to also add utf-8 based chat to 26, but chat changes aren't final yet, so they are done
in one change, after the release, and not two small ones, causing us having to be compliant
to three versions of the packet.

Enable the server to request the client to reconnect.

This can be done with the now extended minetest.request_shutdown([reason], [reconnect]) setting.

Tune and optimise noise parameters

-> Fix server crash with protocol >=25 if a default password is set.
-> Remove some useless and possibly confusion causing code for the TOCLIENT_FIRST_SRP packet handler

-> Fix bug where MoveSomewhere from an infinite source would fill the destination inventory with copies of itself.
-> Fix bug where MoveSomewhere would needlessly call callbacks.
-> Remove trailing whitespaces

Mgv5/mgv7: Remove 'should make cave hole' feature
Remove ravine code

Replaces while loops with proper getfield calls

The doc and the actual behaviour differed.

Also don't show "probably running a different version" message in simple singleplayer mode

Improve TOCLIENT_ACTIVE_OBJECT_MESSAGES robustness for handling invalid data