Automatic reconnection and concurrency improvements

Breaking changes

The following interfaces in the ocppj package changed slightly, affecting existing custom implementations:

• ClientDispatcher
• ServerDispatcher
• PendingRequestState was split into ClientState and ServerState
• ocppj.NewClient and ocppj.NewServer now accept the respective state interface

Websocket clients now include the following new methods:

• SetDisconnectedHandler
• SetReconnectedHandler
• IsConnected

Additions & improvements

• Client websockets automatically reconnect to server after connection loss
• Added network tests for re-connection and timeouts
• Added full support for concurrent requests in ocpp16 and ocpp2
• Automatically clear all callbacks when a charge point/central system is stopped
• Improved test coverage for websockets
• Improved test coverage for ocpp-j layer
• Added logger interface for getting library debug logs
• Added TLS connection state accessor to websocket Channel struct
• Use slices instead of linked lists in FIFO queues

Bugfixes

• Fixed concurrency issues in websockets
• Fixed concurrency and state management issues in ocpp-j dispatchers
• Fixed concurrency issues in ocpp16 package
• Fixed several nil panics in websockets, ocppj and dispatcher
• Don't set clientReadyMap status in request dispatcher if not ready
• Notify charge point of failed requests with onRequestTimeout callbacks