Zom-animals

So I heard the zoose was added? This PR add two new zom-animals: Zomwolf and Zomcougar

Zomwolf spawns in pack and will howl to alert other zombies (most likely other zom-animals), similar to the shrieker zombie but with smaller volume.
Zomcougar will leap around like their living counterpart (and better at combat too).

I also added the relevant entries about new monsters to mtype.h and tile_id_data.h (as instructed in the doc) for tile.

TODO:
- Add description for the monsters, any suggestion?
- Add the howling attack to zombie dog too?