adblock: release 3.8.0

adblock: release 3.8.0

* add support for 'DNS File Reset', where the final DNS blockfile
  will be purged after DNS backend loading (save storage space).
  A small background service will be started to trace/handle
  dns backend reloads/restarts
* add support for the 'null' blocking variant in dnsmasq
  (via addn-hosts), which may provide better response times
  in dnsmasq
* enhance the report & search engine to support
  the new blocking variants. Search now includes
  backups & black-/whitelist as well
* compressed source list backups are now mandatory (default to '/tmp')
* speed up TLD compression
* E-Mail notification setup is now integrated in UCI/LuCI
* update the LuCI frontend to reflect all changes (separate PR)
* drop preliminary dnscrypt-proxy-support (use dnsmasq instead)
* drop additional 'dnsjail' blocklist support (not used by anyone)
* procd cleanups in init
* various shellcheck cleanups
* update readme

Signed-off-by: Dirk Brenken <dev@brenken.org>
(cherry picked from commit 504412ccdbe9e6f1f65b34cf28641ec9aa9b7c22)