Zithorian's Extra Storage Tanks for 2.0

This is a fork of the mod Zithorian's Extra Storage Tanks, ported to Factorio 2.0 and improved upon in many small ways.

Description: The mod adds 4 storage tanks of different footprints and storage capacities, all designed to visually fit together with the vanilla Storage Tank. Their capacities are individually configurable.

Changes: Default capacity was increased for all storage tanks to better fit their visuals; density is 3k/tile for the smaller tanks, 6k/tile for the larger ones. Recipe cost has been rebalanced according to physical dimensions, with larger tanks requiring relatively more steel to craft. An unneeded setting was removed. Stack size was increased for the smaller tanks. Weights for rocket transport were assigned. Descriptions were simplified. Sounds have been updated. And graphics in general have received many small fixes and improvements.