Liquidsoap 1.0.0 beta 3

• Feature: Added of_json to parse json data. Depends
  on json-wheel.
• Feature: Added file.exists and is_directory.
• Feature: Added timeout options for:
  telnet, harbor (server), input.icecast
• Enhancement: finer-grained timeout detection
  for input.harbor and input.http
• Fix: deadlock when disconnecting harbor users
  through server/telnet command.
• Fix: dynlink detection in native mode with old
  versions of ocaml
• Fix: deadlock when an exception is raised during
  startup while the clock is owned by a source
  (e.g. input.alsa). See LS-527 for more details.