This field was used by `pay` to hold the bolt11 description if the bolt11
string used `h` to hash the description (which nobody ever did). If the
`h` field wasn't present, it could contain anything, as it wasn't checked.
It's really useful to have a label for payments (eg. '1 Cuban'), but adding
yet-another option would be painful, so we simply rename 'description'
to 'label' except inside the db.
This means we need to do some tricky parameter parsing to handle array
and keyword JSON arguments, but only until we remove the old name.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
919f390a93