Try out assertj
Create PetriNetComponentNotFoundError

* This error is thrown when searching for a component by it's id
* Propogate this up to the view
* Views then show dialog with the error
* Create displayErrorDialog method in GuiUtils for displaying error
   messages
* Add HistoryItems to creating RateParameters
Create InvalidRateParameter exception

* Propogate this up to adding a rate parameter
Tidy up PlaceView, move token painting into class

* PlaceView no longer uses MarkingView/TokenView, cannot delete these
  classes as they're used elsewhere
* Depricate PetriNetView
Closing last petri net does not crash GUI
Add ability to delete rate parameters in GUI

* Datum now maps to initial datum if it has one
* Remove initialData array
* Change modifiedData to a List
* Create deletedData set
* Create deleteRateParameter method in controller
Deleting rate from petri net removes it from transitions

* Sets the rate of the transition to a normal rate instead
* Added test
Display value of rate parameter in drop down choice
Rate Parameter shows icon on GUI
Fix bug in arc path drawing

* TemporaryArcView always returns false for contains
  previously the mouse event handler in ZoomUI was interacting with
  it instead of the petri net tab
Bind file actions to OS specific command key

* For Mac this is cmd, windows/linux its ctrl
Edit and Type action keyboard shortcuts updated
Bind shortcuts for type actions

* SelectAction is no longer type action
Change shortcuts for actions
SaveAs warning messages and using FileDialog

* FileDialog is more MacOSX-eqsue
* Save as warnings nearly work, they compare petri nets
* Sadly petri net naming does not work yet
* On pressing no two events are fired on macosx needs fixing
Remove naming of unsaved petri nets