- new update url for service "duiadns.net"
- updated public_suffix_list.dat

Signed-off-by: Christian Schoenebeck <christian.schoenebeck@gmail.com>

- cloudflare v1 change syntax of option domain to "host.sub@example.com" like already cloudflare v4 and godaddy to prepare logterm remove of public_suffix_list.dat from package
- change Makefile to be backportable to CC15.05 and working on DD
- change ddns.defaults to prepare future releases of ddns-scripts
- minor fixes

Signed-off-by: Christian Schoenebeck <christian.schoenebeck@gmail.com>

- no longer build public_suffix_list.dat.gz during build #3678
- replace "\s" with "[[:space:]]" inside Makefile because "\s" ignored by some sed versions
- tools/public_suffix_list.sh still available to rebuild public_suffix_list.dat.gz outside OpenWRT/LEDE build system

Signed-off-by: Christian Schoenebeck <christian.schoenebeck@gmail.com>