Add support for continuous scanning
In addition to one-off scans, it would be great to have support for
exitmap should then download the hourly consensus
and have a smart way to scan new relays and re-scan existing relays.
There are a bunch of things to balance here:
- We want to scan new exit relays soon but not always in the first hour, they are part of the network. That would make the scanner too predictable.
- We want to scan existing relays again. But not every hour. Perhaps once a day or every other day.
- We want to run every module over every relay but not immediately after each other as this would make the scanner's behaviour too predictable.