(1) QtilitiesProcess::assignFileLoggerEngineToProcess() will no longer
crash when creation of the file engine failed for some reason. It also
got a new error message parameter and its return type changed from void
-> bool. (2) Logger::newFileEngine() will fall back to the default
formatting engine when a suitable formatting engine cannot be found for
the new file, instead of just failing and returning 0. A warning will be
logged in this case. (3) Proper use of singletons in formatting engines!
Updated Changelog.txt