Implement crocodiles

[VagrantBlackbird]

Crocodiles are creatures with a fixed orientation. They form a one way bridge over water.

• If a Gnome steps on a crocodile from the back or the side, it can walk over it

• If a Gnome tries to step on a crocodile from the front, it gets eaten

• Actions on a crocodile have no effect

• Pouring water on a crocodile has no effect

• If a Gnome is high, it will not get eaten, even when stepping on a crocodile from the front