Rollback safety catches & more verbose command feedback in chat
- The rollback function now checks if the saved rollback timestamp has been read successfully and that the timestamp is at least 1 Jan 2020, to prevent unexpected rollback results in case bogus data got into the datafile somehow.
- Made the commands /spawndragon /killdragon and /removedragon more verbose, so it's clear to the operator what it has done / is going to do.