These are useful for requests:
1. "outpoint": <txid>:<outnum>
2. "feerate": strings or a number
3. "outputdesc": bitcoin-style addresses-as-keys
4. "msat_or_all": amount or "all"
4. "msat_or_any": amount or "any"
5. "short_channel_id_dir": scid with /0 or /1.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>