Fix BlackGui header includes

* Include only what is used
* Use forward declaration when possible
* Sorted includes

refs #598

src/blackgui/components/datasettingscomponent.h

@@ -14,9 +14,12 @@
 
 #include "blackgui/blackguiexport.h"
 #include "blackgui/overlaymessagesframe.h"
-#include <QFrame>
+
+#include <QObject>
 #include <QScopedPointer>
 
+class QWidget;
+
 namespace Ui { class CDataSettingsComponent; }
 
 namespace BlackGui