Removed multiple dialog steps in Source Group setup (issue #723) (#913)

* removed QtSourceGroupWizard, QtSourceGroupWizardPage and context types
* removed isInForm flag of QtProjectWizardContent
* added check of empty source paths
* set project window as parent for message boxes, so they don't get hidden behind main window
* fixed issues when removing and duplicating source groups
* updated project setup tests to no steps

src/lib_gui/qt/project_wizard/content/path/QtProjectWizardContentPath.cpp

@@ -75,7 +75,7 @@ bool QtProjectWizardContentPath::check()
 
 	if (!error.isEmpty())
 	{
-		QMessageBox msgBox;
+		QMessageBox msgBox(m_window);
 		msgBox.setText(error);
 		msgBox.exec();
 		return false;