This set of changes refactors the canonical handling by isolating the business
logic into another type, `Canonical`.
The functionality remains the same, but certain error scenarios are better
handled. Primarily, the commits of the inner `Canonical` type are checked to see
if they exist in the working copy, and if not, provide a more useful message
about which commit was missing or invalid for which DID.
Pay more attention to when a Node ID is displayed in compact form. As
this was sometimes used to save space, e.g. in `rad node status` in
combination with long node addresses (like .onion names), also implement
a compact format for node addresses and use that instead in some cases.
Progress notifications in spinners keep the short form.
Add a test to exercise adding canonical reference rules and pushing new
canonical tags.
A change in `rad id` was required to allow adding a new payload to the document,
i.e. one that does not already exist.
Adding rules is also documented in the man page for `rad id`.
Fintan Halpenny
Lorenz Leutgeb