Fix BlackGui header includes

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

refs #598

src/blackgui/components/commandinput.h

@@ -14,9 +14,14 @@
 
 #include "blackgui/blackguiexport.h"
 #include "blackmisc/identifiable.h"
+#include "blackmisc/identifier.h"
+
 #include <QLineEdit>
+#include <QObject>
 #include <QString>
 
+class QWidget;
+
 namespace BlackGui
 {
     namespace Components