Updated or changed RPC
----------------------

The `fundrawtransaction`, `sendmany`, `sendtoaddress`, and `walletcreatefundedpsbt`
RPC commands have been updated to include two new fee estimation methods "DASH/kB" and "duff/B".
The target is the fee expressed explicitly in the given form.
In addition, the `estimate_mode` parameter is now case insensitive for all of the above RPC commands.