Added 3 new pet sprites and renamed 3 pet sprites.

Added Pet: Tiger Cub, Panda Cub, and Lion Cub. Renamed Pets: Lion Base
-> Mount Lion Base, Panda Base -> Mount Panda Base, Tiger Base -> Mount
Tiger Base. Renamed because these pet sprites were too big and likely
will work better as mounts.
Merge pull request #349 from Shaners/master

Addition of 3 New Pet Sprites and Renaming of 3 Old Pet Sprites.