We only use the proxy for Icecast streaming so there's no need to be
generic.

Includes a merge of radiod and redirectord, updates to more modern Go
idioms, adoption of the higher level etcd concurrency primitives, and
a lot of other minor implementation changes.

The refactor is still incomplete: the daemons won't compile and the
code to start the RPC servers is missing.

This change involves a refactoring of the DNS redirector code, which is
now a bit cleaner and has proper tests.

Split networking is where nodes communicate among themselves on a
private network (for example when behind a NAT infrastructure). This
change adds the --internal-ip option to radiod, that advertises a
separate IP for internal communication.

Adds detailed information about the transcoding hierarchy and parameters.

Refactor the HTTP handler hierarchy to make it simpler.

Replace the ghost logging handler with a simpler one, that fires as soon
as the HTTP request headers are sent (this is a better solution for
long-lived connections).

Add a debug page to track long-lived HTTP request.

Add tests for the HTTP server.

Adds optional transcoding parameters to a Mount. Each node will then
start a master election for every transcoded stream, and the master will
run liquidsoap to re-encode the data. Transcoding mounts are identical
in other respects to normal mounts, except that liquidsoap acts as a
source for them.

Adds a new metric to NodeStatus (MaxListeners) so that it is available
to the traffic control logic.

This change allows us to introduce changes to the inner workings of the
cluster that break backwards compatibility, allowing a smooth transition
to the new format.

Increase robustness of the config watcher by reloading the full
configuration on Etcd errors (fixes an issue with the very common error
401).

Make sure that the Icecast config reload is only triggered if the
configuration has actually changed.

Added a way to stop the node properly, which ensures that we are
tracking all the resources and that there are no deadlocks in the
internal communications.

MasterElection now closes the update channel when it's done.

Introduce node names, allowing a node to have multiple IP addresses.
Also, make the front-end code IPv6-aware and support AAAA records.

This allows running the service on a single port: with the
--enable-icecast-proxy option, all requests can go through
redirectord.