Feature/cdp session with eventemitter

[RLesur]

I open this PR now in order to have a room for discussion for this branch.

[RLesur]

I am really embarrassed by

crrri/R/DevToolsConnexion.R

Lines 27 to 32 in 224df2f

	# if a reponse to a command, emit the callback corresponding to the id
	if (!is.null(id)) {
	method_sent <- private$.commandList[[self$id]]$method
	private$.commandList[[self$id]] <- NULL
	self$emit(method_sent, data)
	}

There are two kinds of messages sent by Chrome:

• Chrome events
• Chrome responses (to commands)

With this implementation, the EventEmitter object throws the same kind of events for Chrome events and Chrome responses: by listening the EventEmitter object, we cannot distinguish Chrome events and Chrome responses . I understand your goal but I fear that could lead to some errors.

I would prefer to keep the distinction between Chrome events and Chrome responses: I will propose some changes in this direction.

[cderv]

It was my understanding that only commands have id. These lines are just emitting the event corresponding to the command sent. Lines after are responding the same way but to method.
What difference would like to have between those two?

[RLesur]

What do you think of that?
I used many events from the chrome-remote-interface library: connect, ready...
I also created new events that would be useful to implement the promises API on top of CDPSession.

[cderv]

Definitely looks good ! It is fine by me.
Should we merge and see how it goes from there with example and test run ?