Adds critter crates

All animals ordered through cargo will arrive in critter crates. These
crates are designed for the safe transport of animals. Critter crates
can only be unlocked from the outside and automatically lock when
closed. You can resist your way out of the crates. Critter crates are
counted as normal crates when sent back to CentComm.

Adds cat crate (cost: 40 points).

Corgi crate now has a 50-50% chance of either containing a male or
female corgi.
Moves critter crate sprites from storage.dmi to closet.dmi.

Removes redundant large animal crates.

This update is pug-ready.