More comments on food production... gotta simplify it!
Update values to reflect simplification of farming.  Use Building_datum::amount_produced() instead of manual loops to find the amount of RES_whatever farms, mines, and sawmills produce.
Farms only produce 1 RES_FARMING but can hire up to 10 peasants.
Move around some fields.
Reflect changes to farming in Interface::minister_food() and Interface::list_farm_crops().
Include the terrain's hunting_difficulty when calculating Map_tile::get_avg_hunting_output().
Increase the hunting_difficulty of most terrain dramatically.
Use Building_datum::amount_produced() where appropriate.  In Player_city::get_food_production(), only divide by 10,000 to match the new farming paradigm.
Rename CROPTYPE_MATERIAL to CROPTYPE_FIBER.