Space Age - Agriculture

[SWeini]

Support agriculture mechanic

• Support AgriculturalTowerPrototype
  It's impossible to calculate speed with 100% accuracy (the crane has a lot of different speeds defined), but we can assume that all AgriculturalTowerPrototype::planting_procedure_points and just assume that the crane speed is not the bottleneck. However, it takes some time for the crane to reach that spot and even longer until the empty spot is replanted.
  AgriculturalTowerPrototype::planting_procedure_points is optional and there is mandatory AgriculturalTowerPrototype::radius
• Support PlantPrototype and create recipes for those
  I believe it makes sense to combine planting & harvesting into a single recipe
  Ingredients are from ItemPrototype::plant_result, respect PlantPrototype::growth_ticks, and use EntityPrototype::minable for products.