Implemented #310 Result info when picking

This included some refactorization to remove the command stuff out of
RiuViewer,
and to communicate the grid index via the source info struct, and not as
a cvfPart::id

ApplicationCode/ModelVisualization/RivSourceInfo.h

@@ -27,10 +27,15 @@
 class RivSourceInfo : public cvf::Object
 {
 public:
+    RivSourceInfo(size_t gridIndex) : m_gridIndex(gridIndex) {}
+
+    size_t gridIndex() const { return m_gridIndex; }
     bool hasCellFaceMapping() const;
     bool hasNNCIndices() const;
 
 public:
     cvf::cref<cvf::StuctGridTriangleToCellFaceMapper> m_cellFaceFromTriangleMapper;
     cvf::ref<cvf::Array<size_t> >                     m_NNCIndices;
+private:    
+    size_t m_gridIndex;
 };