*Industry Satisfaction CB*

Called by town when evaluating whether to grow.

Called for every industry in the town catchment that handles the callback.

Industry returns a value
* bool?
* range (including negative)?

If sum of all returned values > some threshold, grow.
Otherwise not.

Explaining the industry conditions is the job of each industry.

The town might show a general level of industry satisfaction.

Optional ideas

* pass the reason the callback was called, so that other reasons might be added later
* include a specific cargo as a parameter, intended for use by GS (I am less convinced by this as my intent with the cb is to entirely decouple specific town cargos from growth - surely cargo delivery can already just be measured directly if needed?)