message: Mark ProductionTypeTable as const
diff: @@ -16,7 +16,7 @@ using ProductionTypeTable = std::map<ProductType, ProductionCost>;
  * produce. It is up to the individual factory to determine what they are
  * allowed to build.
  */
  -ProductionTypeTable PRODUCTION_TYPE_TABLE =
  +const ProductionTypeTable PRODUCTION_TYPE_TABLE =
  {
  { ProductType::PRODUCT_DIGGER, ProductionCost(5, 10, 5, 5, 2) },
  { ProductType::PRODUCT_DOZER, ProductionCost(5, 10, 5, 5, 2) },
  