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

bin/app/data/gui/window/window.css

@@ -1,16 +1,16 @@
-* {
+#window * {
 	font-size: 12px;
 }
 
-QLabel, QCheckBox {
+#window QLabel, #window QCheckBox {
 	color: black;
 }
 
-QCheckBox::indicator {
+#window QCheckBox::indicator {
 	color: black;
 }
 
-QCheckBox:disabled {
+#window QCheckBox:disabled {
 	color: gray;
 }