Updated toolchains submodule.
Ignore CORRADE_DEPRECATED() macro in Doxygen.
Remove misleading comment.

We need 2.8.8 for much more things.
Adapted to Corrade changes.
Shaders: doc++
Platform: ignore Sdl2Application title in Emscripten.
Platform: add dummy title setting function to NaClApplication.

So the user doesn't need to wrap it in #ifdefs when porting to NaCl.
Add Mesh::id() for consistency.
Xlib.h, I hate you sincerely.
Minor cleanup.
Added EXT_debug_label extension to the list.
external: updated glLoadGen-generated GL headers.

Added EXT_debug_label to them.
Remove obsolete glLoadGen-related workarounds.
Support for object labels from KHR_debug and EXT_debug_label.

Can't test EXT_debug_label, as that is apparently OSX 10.9-only. Added
GL tests for all implemented objects. KHR_debug is selected first, if
that is not available, fall back to EXT_debug_label. If neither is
available, the functions are no-op.

I hope EXT_debug_label gets replaced by KHR_debug later, thus it is now
only "emulated" through KHR_debug enums.
Platform: display label limits in magnum-info.
Fix tests on ES build.
GCC 4.6 compatibility: no std::string::pop_back().
Doxyfile: added annother variant of extension links.
Fixed documentation links to EXT_debug_label.
Use std::string::data() instead of std::string::c_str().

Meaningless changes on meaningless day.