Fix the warning about changing defaultFormat at startup of openflipper
The default surface format must not be changed after the first time it was created, when context sharing is enabled.
- instantiate QCoreApplication before commandline arguments are parsed
- delete QCoreApplication and instantiate QApplication after the default surface format has been set
- don't set default surface format when Core widget is instantiated.
possible problems to check for:
- OpenFlipper settings are initialized when Core is instantiated, but the settings are set before Core is instantiated now. Does it still work?
- Default surface format was set twice in the CoreWidget constructor. once after multisampling was set, once after stereo flag was set. Since there was no new format or default format instantiated afterwards, i considered this redundant and removed these calls to set the default format. is the behavior still correct? If so, some checks may be removed, as they have no effect.
@moebius could you assign someone to double check these changes? I would prefer another set of eyes on them.