We weren't writing out the length of a nested subtype's
dynamicarraylenght, now we do. The trick is to iterate through the
fields on a subtype (since the length field is added separately)
and to also iterate down through the otherfield values as we 'descend'
Instead of val_to_bin/val_from_bin which deal with bytes, we implement
read and write which use streams. This simplifies the API.
Suggested-by: Christian Decker
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This supports infrasructure for creating messages. In particular, it
can be fed CSV from the spec's `tools/extract-formats.py` and then convert
them all to and from strings and binary formats.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: pyln: new module pyln.proto.message
