More specifically, test 'set', 'add', 'remove', 'clear', and 'list'. These are some relatively
complex functions that deal with: case-insensitive duplicate checking, requiring at least 2
channels per relay (auto-remove when a relay is below this threshold), adding/removing things
from existing relays, and more... Sometimes manual testing can't catch all of these complex
situations!
This fixes a bug where you could add duplicate channels using the 'add' command if the same
channel was given with differing cases (e.g. 'relaynext add new-relay channel1@net CHANNEl1@Net').
Also, add a notice when trying to remove a channel that doesn't exist in a relay.
