Allow linking of contour map views

* Place copy of contour map in correct collection
* Allow linking of contour maps
* Improve handling of contour views and 3D views
* Guard nullptr
* Guard assert seen on Linux
* Zoom all on contour map when unlinked to reset zoom
If a contour map is linked to a 3D view, the view can get distorted. Call ZoomAll to reset to sensible defaults.

* Remove default rainbow legend

ApplicationLibCode/ProjectDataModel/Rim3dView.cpp

@@ -331,6 +331,8 @@ QWidget* Rim3dView::createViewWidget( QWidget* mainWindowParent )
 //--------------------------------------------------------------------------------------------------
 void Rim3dView::updateViewWidgetAfterCreation()
 {
+    if ( !m_viewer ) return;
+
     m_viewer->setDefaultPerspectiveNearPlaneDistance( 10 );
 
     this->onResetLegendsInViewer();