Add sfx for non-humanoid characters

At the moment, humanoid characters in the word emit walk/fall/glide sfx, but other body types such as lions and aligators do not.

For things like Quadripeds, the sfx they emit can probably be limited to walking.

It would be nice to emit these sfx at a volume relative to their size, so that a quadriped that is 1/2 the size of a humanoid emits walk sfx at half of the volume.