* 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>