UseCorrade checks existing -std= flags before adding.

This way if CMAKE_CXX_FLAGS already contains c++0x, c++11 or c++1y,
Corrade does not accidentally override.
Adds std::ostream fallback to Utility::Debug.

Debug's operator<< now uses the new Debug::Fallback type to provide a
worst-match overloaded operator<< that only applies when a type has no
operator<< for Debug but does have operator<< for std::ostream&.
Utility: minor cleanup.
TestSuite: ability to compare non-copyable and non-movable types.

There is actually no need to copy anything anywhere. Everything is done
inside Tester::compareWith() function, which holds references to the
input values for whole lifetime of the Comparator object.

Thanks to Chris Chambers (@chris-chambers) for initial idea.
CMake 3.0 compatibility: use AppleClang for Clang on OS X.

Different name because of different version numbers. Also we need to
stay compatible with <3.0, which defines it as "Clang" only.
modules: no backticks in CMake documentation.

That is only for Doxygen.
examples: require at least CMake 2.8.8 everywhere.
Utility: added String::{begins,ends}With().

Also with allocation-free const char[] overload.
PluginManager: avoid needless string copying in plugin registration.

Already done for some time in AbstractPlugin constructor itself, but I
forgot to fix also all these macros and internal functions.
PluginManager: assert instead of failing not-so-gracefully.

In some cases the forgivable behavior caused crash later.
PluginManager: allow plugin to access its associated manager.

The plugin might want to dynamically load and use plugins instead of
making them a hard dependency (e.g. "meta" image import plugin, which
delegates the actual import to another plugin based on detected file
type).

Currently to have access to plugin manager they would need to be always
instantiated through it. This is inconvenient for testing, so
there is a special constructor which takes instance of specific plugin
manager as a parameter.

The manager pointer is exposed only through protected function as
there is no reason for it to be used from outside.
PluginManager: minor cleanup.
PluginManager: properly follow dependencies on destruction.

No more assertions depending on plugin order.
TestSuite: better algorithm for comparing floating-point values.

Still not ideal, but much closer to it than before.
modules: removed obsolete code from UseCorrade.cmake.
modules: display resource files in IDE project view.

Currently the corrade_add_resource() macro was opaque, i.e. it didn't
add anything to project view (in QtCreator, e.g.). Now it adds all
gathered files to make users' lives easier.
modules: display also plugin metadata files in IDEs project view.
CMake: display also all header files in project view of IDEs.

Finally makes the development with QtCreator usable.
Merge branch 'master' into compatibility

Conflicts:
	modules/UseCorrade.cmake