Implement support for request-response style service protocols in comm.js

[marc-portier]

A number of games have non-symmetric message-protocol needs. It should be easy to subscribe such protocols and setup a connection between 2 parties playing either the request-sender or response-provider role.

[karel1980]

I would do this in 1.1. For 1.0 we could get away with only implementing 'peer' and adding calls for both sides of the protocol. The people doing the scratch implementation should then agree on who uses what

[marc-portier]

Totally agree - peer messages with multiple arguments should get them far enough.
The request-response it not that much different IMHO - it just adds some automatic relation between question and answer + provides possibility to create related better labeled blocks to clearly play one side of the protocol.