New Furniture: Standing Tank

Adds a piece of furniture called a "standing tank" to the game, constructed from four metal tanks and a water faucet. It acts like a larger, metal version of the wooden keg, in that it can be used to store large quantities of liquids in a single, central place. The main difference between the two is that the wooden keg holds 600 units of liquid, while the standing tank holds 1200.
Given the impending WELD and GLARE qualities in the concrete PR, I'm not gonna insist on adding a welder & goggles here.  Will make a note for 'em though.