Refactor: forward-declare element type in collection headers

Move the element-type include from each migrated collection header into
its .cpp, leaving only a forward declaration in the header. Follows the
pattern from 9e4d79159 for RimJobCollection, made possible by the
constructor-time PdmObject base check.

ApplicationLibCode/ProjectDataModel/Seismic/RimSeismicViewCollection.cpp

@@ -23,6 +23,7 @@
 #include "Rim3dView.h"
 #include "RimGridView.h"
 #include "RimProject.h"
+#include "RimSeismicView.h"
 
 CAF_PDM_SOURCE_INIT( RimSeismicViewCollection, "SeismicViewCollection", "SeismicViewCollection" );
 

ApplicationLibCode/ProjectDataModel/Seismic/RimSeismicViewCollection.h

@@ -19,13 +19,12 @@
 
 #include "RiaSeismicDefines.h"
 
-#include "RimSeismicView.h"
-
 #include "cafPdmObjectCollection.h"
 
 #include <QString>
 
 class RimSeismicDataInterface;
+class RimSeismicView;
 
 class RimSeismicViewCollection : public caf::PdmObjectCollection<RimSeismicView>
 {