Breaking: removed `rate` and `list_fiat` commands.
This is because the current exchange rates model:
1. Didn't provide enough customization (tied to coingecko and it's currencies only)
2. Often unreliable because sometimes depends on implementation in e.g. electrum
3. Getting rate limited when many daemons are launched
To overcome the problem, we've moved the exchange rates functionality one layer up (like it should have always been), to the Merchants API
This means if you use rate command in your script, you should either use Merchants API directly (maybe your usage of SDK is not required at all), or fetch
exchange rates from your favourite exchange rates provider (more customization)