adding records by ip/loc never seemed to happen
show off split horizon, which already mostly worked
add a method to get all known locations from hub
require classful networks (for now)

the question: can tinydns allow two prefixes for one net?

  %10.2.3:xy
  %10.2.4:xy
require a network, even for world
common code for referring back to hub
emit lines for locations, too
do not allow one code to be present twice
forbid two locations with identical networks
notice when (and why) coercion to Net::IP fails
my face is red: fix ordering of % lines
world needs to be a real location to be exclusive
get rid of an outdated comment and condition
add the always-visible location
allow world/always locations to be named
provide a place to put classless-to-classy prefix map
Merge branch 'split-horizon'