This is from 6e99c5feaf60cb797507d181fe583224309318e9
We renamed the enctlv field to encrypted_recipient_data in the spec, and the
new onion_message is message 513. We don't handle it until the next patch.
Two renames:
1. blinding_seed -> blinding_point.
2. enctlv -> encrypted_recipient_data.
We don't do a compat cycle for our JSON APIs for these experimental
features only used by our own plugins, we just rename.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>