These features were deprecated at least 3 minor releases ago. I found
one mistake which was that `z_validateaddress` had not been placed
behind the `addrtype` deprecated feature; this has been fixed.
Add funding streams to consensus parameters.
Add funding stream payments to coinbase txns generated by the miner.
* Reduce valueBalance for shielded outputs to funding streams.
* Ensure we produce binding signatures in any case where shielded
outputs go to either a funding stream or the miner.