package/maradns: split into subpackages

package/maradns: split into subpackages

For the nameserver alone, maradns is enough. fetchzone/zoneserver are
only used on authoritative/secondary servers, and askmara is just a
query tool probably not needed on embedded devices. Sadly, maradns
itself does not support recursion anymore. For that job, deadwood was
created.

Note that all these daemons don't properly fork into background.
Instead, the author maintains a daemonizing tool called 'duende', which
itself seems to have it's flaws, either. In practice, the deadwood init
script made rcS hang unless it was set to 'DAEMON' in rc.conf. Oh well.

Signed-off-by: Phil Sutter <phil@nwl.cc>