Various bug fixes
- fixes a channel deadlock when > 32 chains monitored (thanks Shultzie for the report)
- problems with restoring state for node-down alerts (thanks m8nky for the report)
- better alarm deduplication
- a few little things flagged by snyk, gocritic, and staticcheck
Note: may require removal of the .tenderduty-state.json file if existing node-down alerts exist.