Add multi-objective support

[ellkrauze]

gc-ml/draft.ipynb

Lines 542 to 559 in 4d47000

	" if goal_value == None:\n",
	" raise Exception(f\"Goal '{self._goal}' was not found in '{summary}'!\")\n",
	"\n",
	" if os.path.exists(summary):\n",
	" os.remove(summary)\n",
	"\n",
	" return goal_value\n",
	"\n",
	" def _get_reward(\n",
	" self,\n",
	" current_state: JVMState,\n",
	" previous_state: JVMState,\n",
	" lower_is_better: bool = False,\n",
	" beta: float = 1.0,\n",
	" ):\n",
	" \"\"\"\n",
	" Get the environment reward. The reward is composed of two terms:\n",
	" `reward = reward_ex + beta * reward_in`,\n",