Execute Script wizard; Now omits last page if no Parameters can be saved

Scripts can define Parameters. Each parameter has a 'Persistable' flag. This indicates whether this Parameter can be saved, e.g. the User can save settings they have entered in the Execute Script wizard and load them when running the Script at a later time.

The 'Load Settings' button on the first page of the Execute Script wizard is now disabled if the Script does not have any 'Persistable' Parameters as is the 'Save Settings' button on the last page of the wizard.

If the Script type cannot be added to a Queue (e.g., it is an Action type Script) and the Script does not have any 'Persistable' Parameters then the last page of the wizard from which you can Save Settings and Add the Script to a Queue is no longer shown.