Fixed minor formatting quirk.
m2v2: unused/useless rpc code removed
Removed inadapted assert from meta1_backend_get_container_properties()
Now decodes multilines with unknown length
meta1_service_url zeroed before liberation
m1v2: better error management on strange output.

Prevents an abusive assert to be raised in calling code.
Early assertions in resolver.
metautils / m1url : JSON codec added + code isolated.