Previously the Controller would be left in a bad state on a master ->
slave transition.

Proxied connections to Icecast are now handled with a simple TCP
proxy that can shutdown each direction independently. Fixes some
connection leaks.

Adds detailed information about the transcoding hierarchy and parameters.

The Stop() method on the liquidsoap controller could have been called
multiple times.

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.

This will limit useless reloads (and related killSources), for instance
when transcoding parameters change. Also, improve the icecast
config generation test.