adblock: release 3.4.0

adblock: release 3.4.0

* preserve DNS cache after adblock processing,
  - 'unbound' and 'named' support this (please check readme)
  - 'dnsmasq' now uses the 'servers-file' directive
    to minimize the reload disruption,
    even though the dns cache will be cleared after SIGHUP
  - 'kresd' dns cache is persistent by upstream default, anyway
    Turris Omnia devices need a small upstream software change
    which is not accepted/implemented yet
* email notification in case of an error or domain count < n
  (default 0, check readme)
* removed securemecca from default config (service has been closed)
* new separate functions for hash compare and list/overall count
* add missing package dependencies
* various clean-ups
* update documentation

Signed-off-by: Dirk Brenken <dev@brenken.org>