cubemap: adapted to Magnum changes.
Adapted to Corrade::PluginManager changes.
modules: updated FindMagnum.cmake from Magnum repository.
Removed redundant `inline` keyword.
Adapted to Magnum changes.
Adapted to texture binding and mesh drawing Magnum changes.
Merge branch 'master' into ports

Conflicts:
	src/text/TextExample.cpp
	src/textured-triangle/TexturedTriangleExample.cpp
	src/textured-triangle/TexturedTriangleShader.h