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.
Remove offensive comment.

EXT_debug_label originated in ES and that was way before KHR_debug. In
fact, KHR_debug is inspired after that.
modules: updated FindCorrade.cmake from Corrade repository.
Use CORRADE_TARGET_WINDOWS instead of _WIN32.
Minor cleanup.
Added EXT_debug_marker extension to the list and GL headers.
New class DebugMessage for inserting debug messages via KHR_debug.

Previously this was done in DebugMarker only via GREMEDY_string_marker
on desktop and EXT_debug_marker on ES, now supporting both three on
desktop and KHR/EXT version on ES. The old DebugMarker is now only a
thin wrapper around DebugMessage, is marked as deprecated and will be
removed in future release.
Platform: display DebugMessage limits in magnum-info.