Added descriptions for rpc command parameters
This also performs the following fixes:
1. delforward parameters are compulsory (required).
2. disableinvoicerequest request added `added` field.
3. invoice request order fixed (label then description, not vice-versa!).
4. listpeers log levels are a proper enum
5. description parameter documented for sendonion requests.
6. deprecatred amount_msat removed from sendpay request.
7. sendpay request partid type fixed to u64 (was u16!)
8. sendpay request localinvreqid type tightened to hash (was hex)
9. sendpay request payment_metadata and description fields documented.
10. sendpsbt request reserve type fixed to u32 (was boolean)
11. utxopsbt request satoshi type fixed to msat_or_all (was msat)
12. withdraw request parameter satoshi is compulsory (required)
13. fundchannel_start request amount is sat, not msat_or_all.
14. openchannel_init request amount is sat, not msat
15. openchannel_init close_to is a string, not hex.
16: invoice labels can be strings OR numbers.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
