Update Limit order price

It would be a nice feature to make it possible to edit the price of an open order. This would essentially just cancel the current order and make a new order, not edit the current one.

I can see that it would be added to the exchange page in the "My orders" list as well as "Open orders" on the dashboard.

Start with the exchange page's "My orders" list and the dashboard's "Open orders" list, then trace the existing order-cancellation flow. The change is done when an open limit order's price can be replaced by cancelling the current order and creating a new one in both locations.

Written by the indexing model from the issue text.