v0.2.0 Non subscription operation, Improved error handling

• Renamed Proxy to OverEngine.
• Added multiple new message types for error and output handling for Envoy and OverEngine.
• Added throughout recover for error handling for both future and stream results.
• Updated OperationMessage, Added GqlError for proper error formats.
• Added capabilities to respond to non-streaming operation using GraphImmediate and StatelessOp.
• Updated OverEngine to be able to execute operation and pipe result back to self with proper error handling.
• Kill / Terminate connection on GraphException.
• Moved onInit to wait after acknowledgement.
• Updated timeoutDuration to allow Duration.Inf which will remove timeout.