• Now Promise saves exception in instance if caught, and reraises it when Promise's result is get, instead of rerasing it during run (possibly even in unknown thread)

• __call__ method added to Promise, so now promises look more like normal callables and are more convenient to use (old run method saved for backwards-compat.)

• Promises handling changed in Dispatcher, so that now dispatcher just runs promises and doesn't need to deal with any possible exceptions as it's work of Promise. Earlier it just logged that something went wrong in case of exceptions.

• Promise handling logic is changed in ConversationHandler, assuming that changed promise may now raise exceptions on res, in that case logger is used for handling

These changes are 1st step on the way to introducing MessageQueue. Had a conversation with @jh0ker about this change proposal

Test results are added below.
test_results.txt