deployment generation assumes symmetrical links #84
Description
Messages are not delivered if a path from receiver -> sender does not exist in nbg. (despite the presence of a sender->receiver pathway).
The deploy.prepare stage should either
- warn the user that the configuration will not work; OR
- insert the reverse edge automatically when absent.
I favour the warning/(fatal) error, since the labelling of reverse is not at all obvious how to do generally: they need to be unique (see #68).