Ported from kapp to KInstance+QApplication. We need still kdeui for kstartupinfo, but this way we avoid:
 - the dbus registration
 - a lot of other gui init done by kapp
 - useless kapp command line options (kstart --icon foo ... won't do the expected)
 - the startupid env reset by kapp, which we then need to set again before starting the app
   (cc to Lubos for post-commit validation of that change)
CCMAIL: l.lunak@kde.org

Also turned the KProcess into a pointer to avoid 'QSocketNotifier: Can only be used with threads started with QThread' warning.

svn path=/trunk/KDE/kdebase/runtime/; revision=608281