Corgi UI and player-controlled behaviours

![corgi_hud](https://cloud.githubusercontent.com/assets/7573912/4554053/74e582b6-4ea6-11e4-8e8d-c128c262a15e.png)

-Corgi now have their very own HUD
-Corgi health upped from 20hp (simple_animal default) to 30hp (still
half of a MoMMi's health)
-player-controlled corgis can now eat food by clicking on it. They can
swallow a food\snack item after 5 bites. Doing so gives them back 1/6 of
their full health (5 HP of 30HP)
-when player-controlled, simple_animals won't randomly move or speak
anymore (this behaviour now only happens when ckey == "null")
-player-controlled corgis now have a verb that allows them to perform
Ian's high speed tail chase/dance. Can be performed while moving for
extra kek.

I plan on giving players a way to play as corgis, something based on the
combined use of a soulstone and a lazarus injector. In the meantime,
it's still useful during adminbus.
Is there a list somewhere of all the span classes in SS13?