Not sure what's new in this commit - still working on selection integration.
Fixed bug where you could only open the graphing window once, subsequent attempts would crash everything.
Fixed the problems with the persistence manager that made it so you can only open the attribute editor (and other dialogs) once per program execution.
Merge branch 'master' of https://github.com/ldevesine/Calvin into selection_changes
Finished making it so clicking a point annotates the graph with that point's data.