Now triggering events when the graph's topology is edited, the graph is completely reloaded or a simulation step is complete
Fixed up generators so that they assign the newly generated graph to the right place. This is broken as the GraphFactory can't empty the existing graph, which is needed in order to preserve all listeners attached to a graph when creating a new instance.
Fixed problem in previous commit.
Fixed bug where the number of susceptible nodes was not set when a graph was loaded, making it impossible to infect any of them through the Infect menu
Fixed a bug where the Infected chart in the right panel did not respond immediately to a Heal All command