config directory for scenarios

[isidoro]

While working in this scenario (http://forum.simutrans.com/index.php?topic=13059.0), I wondered if it would be interesting to have an optional config directory inside the scenario folder that would override the settings of the pak for the scenario.

That way, we'd have: general settings, pak settings, scenario settings...

I came across that while looking for a way to configure that the workers of a factory come from only one city: factory_worker_maximum_towns = 1

[prissi]

The scenario need direct access to this, since these are saved with a game anyway and only apply to new maps.