Performance improvements with large topologies

As a user of the GUI with large topologies, I'd like to have a snappier response.

The Topology View should batch link and device adding events instead of having them come in one by one.

Tabular views should show a loading bar or spinning wheel while waiting for information from the server so it doesn't say "No Links" when there are actually a lot of links but it is taking the server a while to sort them all.