Fix broken registrar persistence, multiple prospector tracking issues, and (re?)implement configurable dead_time
Prospector now detects file rotation while it is not running

reported in issue #144
DRY - Restructure prospector
Small logging changes

- Add an extra log message for file rename to improve log readability
- Further log readability improvements
- Tweak logging to remove any confusion
Move default values to constants + bug fixes

- Also remove constraint on dead time and fix <10s dead time causing issues with new files
- Only clean out prospector info of files we've stopped harvesting
- Tidy and improve variable naming
- Tidy registrar
- Tweak startup events and always write registry
- Fix a comment referring to missing commits