QCommandLineParser::process(arc, argv)

It would be useful to pass arc and argv to QCommandLineParser. This allows us to use it before creating an QCoreApplication instance.

Now it's only possible to obtain an arguments list from the QCoreApplication::arguments() and pass it to QCommandLineParser::process(). Without QCoreApplication one need to deal with character encodings, system API and other low-level things and workarounds to get the program arguments in a reliable and cross-platform way.