Analyse regex blacklist

[yubiuser]

This adds the new option -r which will analyse blacklist regex as well. It first creates a list of all visited domains (from pihole-FTL.db) and then checks each domain against all regex. Output is a table with all regex blacklist and the number of visited domains that would have been been blocked by this regex.

Note Depending on the amount of visited domains, the number of regex entries and the hardware/CPU this calculation needs some time (were talking about minutes!). This is also the reason users need to enable regex analysis manually and they are off by default.

Note 2 The Pi-hole's regex engine can do some very fancy stuff (e.g. blocking based on the query type). The internal test (pihole-FTL regex-test) can not test for all those rules as it only takes the domain into consideration. There might be more edge cases that are not covered by this test. Therefor, the number of covered domains by some regex might be understimated.