message: Mark product storage value table as const
diff: @@ -11,7 +11,7 @@ using namespace NAS2D::Xml;
  /**
  * Space required to store a Product.
  */
  -std::map<ProductType, int> PRODUCT_STORAGE_VALUE =
  +const std::map<ProductType, int> PRODUCT_STORAGE_VALUE =
  {
  { ProductType::PRODUCT_DIGGER, 10 },
  { ProductType::PRODUCT_DOZER, 10 },
  