Model Eryops and pt_BR.lang

- Eryops health 20 hit points (10 hearts), not sure if it is correct.
- Eryops speed is similar to a zombie.
- Eryops attack is 1 heart (normal difficulty).
- Eryops basic AI. It does not swim yet.
- Eryops spawns in beach biome.
- pt_BR.lang done (translated from the en_US.lang).

Notes:
Eryops does not open its mouth, because the variable mouthTick is server
side only. We have to send a pkt to the client in order to open its
mouth when attacking.