Support multiple fan-out

If multiple fan-in is supported (a single PI can receive from N RIs, N>1), currently fan-out is limited to be 1 (a RI must be connected to a single PI).

This requires that if a function F1 needs to send a message to many receivers at the same time, multiple RIs must be created in F1, and each message sent in sequence (if synchronous) or in parallel (if asynchronous) through all RIs.

Having fun-out > 1 would simplify hugely the design and the layout at system level, as:

• It would require less RIs
• If combined with the use of containers, it would require less connections, e.g. a connections from the single RI to a Container's PI, and then multiple connections from the Container's PI to all the PIs of the contained functions.

This would allow for the effective definition of a hierarchical component-based system, to support decomposition, delegation, and finally the actual design of of large complex systems.