A better way to structure commands across multiple packages

- So that the preferences for commands to fire are not restricted on the
  ordering of their packages.

Cascading response with a stop on trigger

- Say bot responds to weather queries.  Define trigger to be the same
  for multiple calls, but one call may be some kind of trap for a funny
  response and also results in subsequent queries (like detailed
  weather information) to not be reported.
- Could be marked as an exclusive response, if triggered.

Globally substitute all response with the replacement texts.
