Changing to Complete status would ensure all proofs are closed in addition to all tasks and issues

Currently, a project can't be changed to Complete status until all tasks are complete and all issues are closed. It would be helpful if all proofs were required to be closed before the status can be changed to Complete. 

The system will remain much cleaner if all parts of the project are closed. This could be a manual change to the proof status, or ideally, the system could close the proof automatically when the project status is changed to Complete.