Fusion editor defects and loose ends

[jng]

This ticket is an umbrella ticket for the fusion editor

• Delete button in widget configuration dialog does not remove the underlying widget from the widget set
• The the map editor needs to be re-designed as it is currently hardcoded for certain map providers. Most particular, it will only allow 1 MapGuide map provider (and a choice of Bing/Google/Yahoo providers). Thus the editor prevents the ability to have a MapGroup with multiple MapGuide maps in it (eg. A dynamic map definition and a tiled map definition together)
• Add a new validation rule that checks if any Map Definitions conform to the Popular Visualisation Mercator coordinate system if it is part of a MapGroup that also has a Bing/Google/Yahoo provider in it.