Emit messages without message flows

[nikku]

Is your feature request related to a problem? Please describe.

In technical modeling you often times don't model message flows, as these do not have execution semantics. Instead you rely on the actual messages defined to correlate messages that are thrown somewhere else:

Describe the solution you'd like

In the absence of message flows the simulator correlates based on active scopes with message subscriptions.

Describe alternatives you've considered

None.

Additional context

Came up in forum.