Add runtime service to context
Such a runtime service should provide the following functionalities:
- connect two ports
- send signals (init + start)
- create and start a stage within a new thread
Use cases:
- distributor: creates new output port, connects its and another port, and sends the signals
- merger: creates new input port and connects its and another port
- divide & conquer: duplicates itself, connects the ports, send the signals, and create/starts a new thread