Use less relative includes, some of them were wrong

The example now includes them, so we can detect build failures
if they get wrong again

Fixes #140

src/private/widgets/QWidgetAdapter_widgets_p.h

@@ -21,7 +21,7 @@
 #ifndef KDDOCKWIDGETS_QWIDGETADAPTERWIDGETS_P_H
 #define KDDOCKWIDGETS_QWIDGETADAPTERWIDGETS_P_H
 
-#include "../../docks_export.h"
+#include "kddockwidgets/docks_export.h"
 
 #include <QWindow>
 #include <QWidget>