Improved logic for _is_game_over

[helpingstar]

gym-game2048/gym_game2048/envs/game2048.py

Lines 193 to 210 in 0fec66f

	if self._is_reach_goal():
	reward = 1
	terminated = True
	else:
	self.spawnblock()
	terminated = self._is_game_over()
	if terminated:
	self._update_best_score()
	reward = -1
	else:
	reward = 0
	else:
	self.is_legal = False
	terminated = False
	reward = 0
	self._update_legal_moves()

When action_mask is all 0, it means the game is over. The current code uses the same logic twice. This can be improved.