Remove duplicate Vec3.__eq__/__neq__

My bad, I didn't see https://github.com/py3minepi/py3minepi/pull/26
introduced them as duplicates when I merged
e697c9cf5173881cf1d5e43f2c2aff5de7aa8256
Merge branch 'master' into feature/remove-duplicate-eq
Merge pull request #43 from py3minepi/feature/remove-duplicate-eq

Remove duplicate Vec3.__eq__/__neq__