Add startup progressbar to Qt 5 GUI

And related tweaks.
Add support for log file compression
Ignore unknown CLI arguments
Set Python argv asynchronously in Qt 5 GUI & pass additional arguments

With Qt 5 GUI the Python part of modRana is started from QML and thus sys.argv
is not set by default.
Make the main part of the modRana Qt 5 GUI startup fully asynchronous
Add a method for getting values during Qt 5 GUI startup

By getting the values in "batch" we reduce the number of Python <-> QML roundtrips
and make event coordination for the asynchronous startup easier.
The modRana Qt 5 GUI startup is now fully asynchronous ! :D

The remaining synchronous calls we replaced by asynchronous function
call that gets all the needed values and a callback function that does
the rest of startup.

This change also made a pretty nice cleanup possible and the modRana Qt 5 GUI
startup code now looks much better! :)