Added width specifier to format.

check Qt Version when command line arguments are parsed and disable stereo for qt version 5.7.0 and 5.7.1

Core: consistently check for splashscreen availability.

Core::finishSplash had an unguarded callsite that would cause a crash if
the splash screen is disbled. This change makes everything a bit simpler.

See merge request !168

Core::finishSplash had an unguarded callsite that would cause a crash if
the splash screen is disbled. This change makes everything a bit simpler.

* behaviour in the build documentation

changed the check for debug console to check if NDEBUG is not defined as
it is the standard behaviour