Topology providers should provide a description for display

It's not immediately clear to a new user what (for instance) an "Enhanced Linkd" topology is. Topology providers should be required to provide a short description to be shown to users. How to show it is not so important, could be a tooltip in the topo map's View menu or (maybe better) a persistent control that tells the user which topology she's currently viewing and also displays the description. Whatever display strategy, we should have the data in the model.