added: ParseJSON function to convert JSON into a tree of CJSONElement using libyajl as the parser
added: moved CClientsManager to the new JSON api
added: JSON action to delete a client
refactor: move message pipe into CMessagePump and derive other classes from it
refactor: move sending of messages about clients added/deleted into CClientsManager
added: json action to update a client's instances, pregain, postgain and controls
added: check ladspa plugins for validity, remove any that are incorrect