Create follow-on repayment proposals re denomination and per-cycle limits

[cbeams]

Carried over from the task list in bisq-network/proposals#209 (comment):

• create proposal about how repayments will be denominated as discussed in Repay victims of the April 2020 security incident using BTC trading fees proposals#209 (comment)
• create proposal about maximum per-cycle repayment limits as discussed in Repay victims of the April 2020 security incident using BTC trading fees proposals#209 (comment)

Targeting Cycle 14 for this. The idea is to get repayments and repayment tracking up in Cycle 13. Once everything is in motion we can then decide about these matters.

[cbeams]

Per bisq-network/projects#31 (comment), @ripcurlx has taken over the victim repayment project, and I've just assigned this task to him accordingly.