Please add the node id to progress messages from the WebSockets implementation (also towards parallel execution)

In the websockets protocol, progress messages don't contain the node id, which has to be deducted by the previous "executing" message. If parallel execution was enabled, such protocol would not work anymore. So I suggest to add the node id also to the progress messages, so that programs using the WS protocol can be already "future-proofed" and be prepared for parallel execution.

[EDIT]: for similar reasons also an "execution finished" message for nodes would be required (unless 100% progress already means "finished", not sure about that)