RGB render mode

[sparisi]

Added render_mode="rgb_array" as in Gym. Render uses the same color palette as human mode. Env can be wrapped around Gym wrapper to learn from pixels by doing

import minatar
import gym
from gym.wrappers.pixel_observation import PixelObservationWrapper

env = gym.make('MinAtar/Seaquest-v1', render_mode='rgb_array')
env = PixelObservationWrapper(env, pixels_only=True)

Observations size is (10, 10, 3) and can be resize using Gym wrappers. Upscaling works well.