ENH: runTimePostProcessing FO camera update

- Removed the camera 'mode'
    - The (old) static camera was only appropriate when parallel
      projection was inactive, and the view was centred at (0 0 0)
    - Camera input now always requires 'position' and 'focalPoint'
    - Clip box is now optional.  Note that this is applied after the
      camera
      set-up and so will override the camera position
    - View angle is only appropriate when not using parallel projection
    - Zoom now required, applied after all other operations
      - 1 = do nothing, >1 = zoom in, <1 = zoom out

    Example input:

        camera
        {
            // Total number of frames to generate
            nFrameTotal 1;

            // Parallel projection flag
            parallelProjection no;

            // Optional clippling box
            clipBox     (-0.0206 -0.0254 -0.0005) (0.29 0.0254 0.0005);
            focalPoint  (0 0 0);
            up          (0 1 0);
            position    (0 0 1);
            viewAngle   20;
            zoom        1.1;
        }

src/functionObjects/graphics/runTimePostProcessing/scene.H

@@ -49,6 +49,7 @@ SourceFiles
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+class vtkActor;
 class vtkRenderer;
 class vtkRenderWindow;
 
@@ -58,22 +59,12 @@ namespace functionObjects
 {
 namespace runTimePostPro
 {
-
 /*---------------------------------------------------------------------------*\
                            Class scene Declaration
 \*---------------------------------------------------------------------------*/
 
 class scene
 {
-public:
-
-    enum modeType{mtStatic, mtFlightPath};
-
-    NamedEnum<modeType, 2> modeTypeNames_;
-
-
-private:
-
     // Private data
 
         //- Reference to the object registry
@@ -88,7 +79,7 @@ private:
         //- Read camera properties
         void readCamera(const dictionary& dict);
 
-        //- Read solour properties
+        //- Read colour properties
         void readColours(const dictionary& dict);
 
         //- Disallow default bitwise copy construct
@@ -108,9 +99,6 @@ protected:
 
         // Camera settings
 
-            //- Mode
-            modeType mode_;
-
             //- Position
             autoPtr<Function1<point>> cameraPosition_;
 
@@ -123,12 +111,20 @@ protected:
             //- View angle
             autoPtr<Function1<scalar>> cameraViewAngle_;
 
+            //- Zoom: 1 = do nothing, >1 = zoom in, <1 = zoom out
+            //  - perspective mode: reduces view angle
+            //  - parallel mode: manipulate parallel scale
+            autoPtr<Function1<scalar>> cameraZoom_;
+
 
         // Scene management
 
             //- Clipping box
             boundBox clipBox_;
 
+            //- Clipping box actor
+            vtkSmartPointer<vtkActor> clipBoxActor_;
+
             //- Parallel projection flag
             bool parallelProjection_;