WIP - added project data model files for well log plots

Added command feature for adding new well log plots (right-click "Plots"
in the project tree view). Will create dummy Qwt widget added as an MDI
window.
TODO: Complete the relations between the entities, and add
properties/property editors. Create more advanced viewer widget for
plotting of multiple traces with multiple curves. Harmonize MDI stuff
with 3D viewers.

ApplicationCode/UserInterface/RiuMainWindow.h

@@ -43,6 +43,7 @@ class RimEclipseCase;
 class RiuProcessMonitor;
 class RiuResultInfoPanel;
 class RiuViewer;
+class RiuWellLogPlot;
 
 namespace caf
 {
@@ -82,6 +83,10 @@ public:
     void            addViewer(RiuViewer* viewer);
     void            setActiveViewer(RiuViewer* subWindow);
 
+    void            addWellLogViewer(RiuWellLogPlot* viewer);
+    void            removeWellLogViewer(RiuWellLogPlot* viewer);
+    void            setActiveWellLogViewer(RiuWellLogPlot* subWindow);
+
     void            setResultInfo(const QString& info) const;
 
     void            refreshAnimationActions();
@@ -123,6 +128,7 @@ private:
     void            updateRecentFileActions();
 
     QMdiSubWindow*  findMdiSubWindow(RiuViewer* viewer);
+    QMdiSubWindow*  findMdiSubWindow(RiuWellLogPlot* viewer);
 
     void            storeTreeViewState();
     void            restoreTreeViewState();