GCC 4.7 compatibility: hide deprecated warnings in internal code.
package: Audio library is disabled by default.
Platform: proper suffix for EGL_OPENGL_ES3_BIT constant.

Apparently not tested once.
modules: different libraries for OpenGL ES 2.0/3.0 in FindMagnum.cmake.

Also apparently not tested at all.
modules: libGLESv3 actually really exists.

The world is actually sane.
Hardened checks for OpenGL ES version.

There is no ES 2.5 or 3.01 and this way we can properly check for
garbage returned by `glGet(GL_VERSION_M*OR)` (e.g. version 2674.-2O8539
would pass here).
Print separate major/minor integers for unsupported version.

This message:

    Context: unsupported OpenGL version (1, 3).

Is better than this:

    Context: unuspported OpenGL version 130.
Updated toolchains submodule with Android support.
modules: updated FindCorrade.cmake from Corrade repository.
external: updated Optional with Android support.
Explicitly enable OpenGL ES when targeting Android.
Build static libraries for Android.

Same reasoning as in Corrade.
Apparently Android is something like newlib.
package: Android ARM and x86 development ArchLinux PKGBUILDs.
Unique exit code for each failure in Context::Context().

Make it less annoying to debug things on platforms which send all
standard output to /dev/hell without any easy way to override that. Yes,
I'm looking at you, Android.
Advertise particular application libraries only on supported platforms.
doc: Android building documentation.
Advertise Android support.
We don't have any platform support for Android yet.
Platform: another round of insane documentation updates.

Each class should now have *everything* needed in its documentation,
nothing is left out. Most of the text was taken from README in
magnum-bootstrap repository.