Utility: more portable way to find out if a file exists.

Spent TWO HOURS	trying to get this working on MinGW. Aargh.
doc: prefer to use NaCl newlib.
doc: Emscripten building documentation consisted of brain farts.
UseCorrade.cmake: embarrassing typo.
Utility: added Resource::list() function.
Utility: fixed compilation with Clang.
Utility: fixed unaligned read in MurmurHash2.

Causes Emscripten to behave strangely if data % 4 != 0. May fail also on
ARM.
examples: properly specify CMAKE_MODULE_PATH.

Was working when Corrade was built and installed with WITH_FIND_MODULE
enabled (my case), but failed everywhere else due to FindCorrade.cmake
not found. Many thanks to @biosek for the report..
Interconnect: fix documentation typo.
Interconnect: include full information in both StateMachine signals.
Interconnect: update docs.
Interconect: added StateMachine::stepped() signal.

This thing is now officially the craziest implementation I have ever
created. Muhehehehahahoho.
Fix: inexistent -> nonexistent.

No publicly visible change, tests only.
Utility: open resource configuration files read-only.

The variable was const already, but this is even more hardened.
Utility: improve and test Resource compiler error reporting.
PluginManager: verify that instance is returned only from proper manager.

Currently fails. How could I forget to check this obviously dangerous
error?!
PluginManager: return instance only from proper manager.

The tests now pass again.
examples: fix compilation when Corrade is installed w/o WITH_FIND_MODULE.

The examples expected FindCorrade.cmake to be installed in system
location.
doc: crosslink examples with CMake macros documentation.

Also removed obsolete information from PluginManager example.
dox: fixed PluginManager example code listings.