Minimum Relay Fee not checked until last step of trade

[elliot-tio]

A trade for sell orders (fill or kill) is allowed to reach the last step where seller needs to collect payment (HTLC step 4) but cannot do so because of Error: 66: min relay fee not met

*stuck in this step

[David-Owen-Walker]

When buying or selling BTC or (blank) EQB, there is a bug which can make a transaction impossible to complete. If only a small quantity of currency is being traded, the payment may be smaller than the minimum relay fee and therefore uncollectible. This means we have four cases to handle

• Prevent someone from making an order that is too small (in either currency)

• Prevent someone from making an offer that is too small (in either currency)

• Prevent someone from making an offer that leaves the order with a remaining amount that is too small (in either currency)

• Prevent someone from accepting an offer that leaves the order with a remaining amount that is too small (in either currency)

These are some simple error checks on the server and new error messages on UI.