Added Raw serialization type

[muka]

This PR introduce a raw serialization type which allow to bypass the binarypack serialization mechanism and delegate it to the user.

With this modification I have been able to exchange messages with a server-side port of peer.

Porting binarypack to other languages is challenging but using raw byte exchange or other serialization libraries (like proto buffer or avro) would be significantly easier.

I tried to implement test but seems on node side is not possible to go much further testing data connections

This mark also a progress in #759 for interoperability direction

Thank you

[AndySpider]

As far as I know, the json or binary serializations can be bypassed if user specifies a custom value to the serialization parameter (like a "raw" string). It's un-documented though...

[muka]

Can you share an example? thanks

[AndySpider]

@muka It's quite simple, just set the serialization parameter to a self-defined value when connect, like below,

const peer = new Peer('myId', ...);
const dataConn = peer.connect('idToConnect', {
    serialization: 'abcdef'              // any string other than the official "binary" or "json" will result in raw serialization type
});

[muka]

@AndySpider thank you, it was indeed that simple :)

I would suggest to add a Raw item to SerializationType that in practice does what I was proposing in this