Adds a new Heavy duty cargo wagon with 120 inventory slots unlocked by Metallurgic Science, crafted using tungsten and molten metal on Vulcanus. It's a bit heavier than a standard cargo wagon, but it has decreased friction and greatly increased braking force, great for long trains.

It's intended to be used once stack inserters are relevant, as standard cargo wagons simply can't compete with a stacked turbo belt. Does this actually fix that issue? I don't know, I haven't tested it enough! I sure hope it does!

Also, fluid wagons have their storage space halved, down to 25k. The idea is to make moving molten metal by rail less powerful, but it might just be annoying.