doc: use unique section names.
modules: updated FindCorrade.cmake.
Dropped GCC 4.6 support.
package: replaced MinGW32 PKGBUILD with MinGW-w64 one.
Be consistent and use our own platform definitions.
modules: updated FindCorrade.cmake and FindMagnum.cmake.
Doc++
package: added MinGW-w64 Jenkins CI configuration.

Also mentioned NaCl in building docs.
modules: added missing FindOpenGLES3.cmake.

I wonder how this worked before.
Updated toolchains submodule.
package: adapted Emscripten PKGBUILD to emscripten-git package in AUR.
Merge commit 'edab5386a5c12fa519' into compatibility
Merge commit '3c6ca7dfda25aa2fcf' into compatibility

These two commits drop GCC 4.6 support, which we want to preserve in
compatibility branch.
modules: updated FindMagnum.cmake.
package: removed MinGW32 Jenkins CI configuration.

Can't test it on my system anymore.
Merge branch 'master' into compatibility

Conflicts:
	doc/building-plugins.dox