Maybe add progress bar for GUI tabulation

[HEdingfield]

trafficstars

See: https://stackoverflow.com/questions/34357005/javafx-task-update-progress-from-a-method

And: https://stackoverflow.com/questions/23701639/call-tasks-updateprogress

[chughes297]

I think this would be really great UI/UX - right now it's not obvious where to look for any signs of tabulation progress

[yezr]

#679 and #825 have been written to implement this! Closing as a dupe