adblock: update 1.2.1

adblock: update 1.2.1

* small optimizations & cosmetics

adblock: release 1.2.0

* rework download/backup/restore handling
* rework firewall handling
* refine whitelist parsing
* changed default null-ip to 198.18.0.1 to prevent conflicts with bcp38
* spread traffic from ad servers (port 80/443) on two uhttpd instances,
this fixes timeouts on sites with many ssl ad server connections, i.e.
youtube.com
* provide statistics & last runtime for LuCI interface
* documentation update

Signed-off-by: Dirk Brenken <dev@brenken.org>
(cherry picked from commit 8ab3d8bdc2535c208d3baa04fbf9269c080030de)
(cherry picked from commit 672dd10b101de5013e2df1d6a4b2d287b782e42f)