Made the critter "crate" a child of closet.

It still functions as before, except you can weld it now. Welding it
increases the breakout time from 45 seconds to 120. The lock still works
after someone has broken out of the crate. Icons cut from storage.dmi,
put into closet.dmi.
The supply controller now recognizes the critter "crate" as a crate.