[Gui] So headers: remove unused includes

- also sort out some headers to be used in precompiled headers
- also move a boost header to precompiled headers

src/Gui/SoFCSelection.cpp

@@ -24,29 +24,29 @@
 
 #ifndef _PreComp_
 # include <QString>
+# include <Inventor/SoFullPath.h>
+# include <Inventor/SoPickedPoint.h>
+# include <Inventor/actions/SoGLRenderAction.h>
+# include <Inventor/actions/SoHandleEventAction.h>
 # include <Inventor/details/SoFaceDetail.h>
 # include <Inventor/details/SoLineDetail.h>
+# include <Inventor/elements/SoLazyElement.h>
+# include <Inventor/elements/SoMaterialBindingElement.h>
+# include <Inventor/elements/SoOverrideElement.h>
+# include <Inventor/elements/SoWindowElement.h>
+# include <Inventor/events/SoKeyboardEvent.h>
+# include <Inventor/events/SoLocation2Event.h>
+# include <Inventor/events/SoMouseButtonEvent.h>
+# include <Inventor/misc/SoState.h>
 #endif
 
-#include <Inventor/SoFullPath.h>
-#include <Inventor/SoPickedPoint.h>
-#include <Inventor/actions/SoGLRenderAction.h>
-#include <Inventor/actions/SoHandleEventAction.h>
-#include <Inventor/elements/SoLazyElement.h>
-#include <Inventor/elements/SoOverrideElement.h>
-#include <Inventor/elements/SoWindowElement.h>
-#include <Inventor/events/SoKeyboardEvent.h>
-#include <Inventor/events/SoLocation2Event.h>
-#include <Inventor/events/SoMouseButtonEvent.h>
-#include <Inventor/misc/SoState.h>
-
 #include "SoFCSelection.h"
 #include "MainWindow.h"
-#include "SoFCInteractiveElement.h"
 #include "SoFCSelectionAction.h"
 #include "SoFCUnifiedSelection.h"
 #include "ViewParams.h"
 
+
 // For 64-bit system the method using the front buffer doesn't work at all for lines.
 // Thus, use the method which forces a redraw every time. This is a bit slower but at
 // least it works.