dbd2ea07b5 Add kilo weight unit conversion (yancy)
Pull request description:
The FeeRate module defaults to sats per `kwu` so when doing fee calculations, it would be convenient to easily convert weight to the same units.
ACKs for top commit:
Kixunil:
ACK dbd2ea07b5
tcharding:
ACK dbd2ea07b5
apoelstra:
ACK dbd2ea07b5
Tree-SHA512: fe26b631cf474f1dca627a4d21e9052c80f8ada9a0eb635c46b7f8f42095671b9b161fb5012b723699008372faf7668507d5e92bde7d1808d389f85dba33529b