Make tank tops skintight

...because it's silly to not be able to wear a tank top under something
if you can wear an undershirt under something.
Fix "Louisville Slaughterer" (was "Slaghterer")
Allow teapots in "clean water" recipe

...because if a coffee maker can heat water enough to kill pathogens,
surely a teapot over a fire can.
Add "small metal tank" recipe

This recipe lets you craft a small metal tank for a motorcycle (in the
same way you can already craft a metal tank for a car or steel
jerrycan).

Small metal tanks are made of aluminum whereas regular tanks are steel,
so it's a little fishy that they're made from the same steel sheet
metal, but a more elegant solution will have to wait.
Merge pull request #6166 from dholmes215/master

Minor content changes