Finish basic visualization editor implementation

The Visualization and Visualization Set editors are now fully
functional.  You can create, edit, and rearrange sets, and they're
now stored in the project file.

SourceGen/MainController.cs

@@ -2161,7 +2161,7 @@ namespace SourceGen {
             mProject.VisualizationSets.TryGetValue(offset, out VisualizationSet curVisSet);
 
             EditVisualizationSet dlg = new EditVisualizationSet(mMainWin, mProject,
-                mOutputFormatter, curVisSet);
+                mOutputFormatter, curVisSet, offset);
             if (dlg.ShowDialog() != true) {
                 return;
             }