Worker Automation Improvements

Workers don't care about Clean Fallout time or cost, workers no longer
have a 2x bias to chop forests after Optics, workers now evaluate tile
faith yield, Inca workers know that hills are maintenance-free, Dutch
workers clean marshes on tiles with resources, AI Celt workers no longer
leave forests unimproved if they are in the Industrial Era or later,
automated workers value strategic resources of which the player has none
over strategic resources of which the player has some but has spent it
all