v4.1.4

Improvements since 4.1.3:

1. #341: Deprecate "blacklist4," add replacement "denylist4."
2. #342: Add /32 to the generic denylist again. (And remove secondary addresses, since nobody has actually requested them.)
3. #343: Clarify some documentation. (WIP)

I also largely rewrote the "intro-xlat" documentation page, to reflect the changes from the MAP-T branch.