Connection between the original proposal and the submitted proposal

[DJWalker42]

From comments in issue #271, for quick reference:

Paul Harrison wrote:

The intention is the the original is not set to submitted - remember that you can potentially submit the same proposal to several telescopes, so you want it there ready to submit to the next - To see submitted proposals then the explicit SubmittedProposal objects should be queried. That is also why the original is cloned.

There really needs to be a separate table (outside the model), that records which original proposal IDs get submitted to which cycles.. The submitted status was put into the model as a quick hack, so that the submitted proposals did not appear, but perhaps this is a case where it would be better if the submitted proposal were actually a sub-class!

The alternative is that the "related proposals" part of the model could be used - though this was originally envisioned to point to less close relationships than just submitted.