Gym

Major Change:
- Replaced Atari-Py dependency with ALE-Py and bumped all versions. _This is a massive upgrade with many changes, please see the [full explainer](https://brosa.ca/blog/ale-release-v0.7)_ (JesseFarebro)
- Note that ALE-Py does not include ROMs. You can install ROMs in two lines of bash with AutoROM though (`pip3 install autorom` and then `autorom`), see https://github.com/PettingZoo-Team/AutoROM. This is the recommended approach for CI, etc.

Breaking changes and new features:
- Add `RecordVideo` wrapper, deprecate monitor wrapper in favor of it and `RecordEpisodeStatistics` wrapper (vwxyzjn)
- Dependencies used outside of environments (e.g. for wrappers) are now in 'other' extra' (jkterry1)
- Moved algorithmic and unused toytext envs (guessing game, hotter colder, nchain, roulette, kellycoinflip) to third party repos (jkterry1, Rohan138)
- Fixed flatten utility and flatdim in MultiDiscrete sapce (tristandeleu)
- Add `__setitem__` to dict space (jfpettit)
- Large fixes to .contains method for box space (FirefoxMetzger)
- Made blackjack environment properly comply with Barto and Sutton book standard, bumped to v1 (RedTachyon)
- Added `NormalizeObservation` and `NormalizeReward` wrappers (vwxyzjn)
- Add `__getitem__` and `__len__` to MultiDiscrete space (XuehaiPan)
- Changed .shape to be a property of box space to prevent unexpected behaviors (RedTachyon)

Bug fixes and upgrades:
- Video recorder gracefully handles closing (XuehaiPan)
- Remaining unnecessary dependencies in setup.py are resolved (jkterry1)
- Minor acrobot performance improvements (TuckerBMorgan)
- Pendulum properly renders when 0 force is sent (Olimoyo)
- Make observations dtypes be consistent with observation space dtypes for all classic control envs and bipedalwalker (RedTachyon)
- Removed unused and long depricated features in registration (Rohan138)
- Framestack wrapper now inherits from obswrapper (jfpettit)
- Seed method for `spaces.Tuple` and `spaces.Dict` now properly function, are fully stochastic, are fully featured and behave in the expected manner (XuehaiPan, RaghuSpaceRajan)
- Replace `time()` with `perf_counter()` for better measurements of short duration (zuoxingdong)

Gym 0.19.0 is a large maintenance release, and the first since jkterry1 became the maintainer. There should be no breaking changes in this release.

New features:
- Added custom datatype argument to multidiscrete space (m-orsini)
- API compliance test added based on SB3 and PettingZoo tests (amtamasi)
- RecordEpisodeStatics works with VectorEnv (vwxyzjn)

Bug fixes:
- Removed unused dependencies, removed unnescesary dependency version requirements that caused installation issues on newer machines, added full requirements.txt and moved general dependencies to extras. Notably, "toy_text" is not a used extra. atari-py is now pegged to a precise working version pending the switch to ale-py (jkterry1)
- Bug fixes to rewards in FrozenLake and FrozenLake8x8; versions bumped to v1 (ZhiqingXiao)
-Removed remaining numpy depreciation warnings (super-pirata)
- Fixes to video recording (mahiuchun, zlig)
- EZ pickle argument fixes (zzyunzhi, Indoril007)
- Other very minor (nonbreaking) fixes

Other:
- Removed small bits of dead code (jkterry1)
- Numerous typo, CI and documentation fixes (mostly cclauss)
- New readme and updated third party env list (jkterry1)
- Code is now all flake8 compliant through black (cclauss)

* Now your `Env` and `Wrapper` subclasses should define `step`, `reset`, `render`, `close`, `seed` rather than underscored method names.
* Removed the `board_game`, `debugging`, `safety`, `parameter_tuning` environments since they're not being maintained by us at OpenAI. We encourage authors and users to create new repositories for these environments.
* Changed `MultiDiscrete` action space to range from `[0, ..., n-1]` rather than `[a, ..., b-1]`.
* No more `render(close=True)`, use env-specific methods to close the rendering.
* Removed `scoreboard` directory, since site doesn't exist anymore.
* Moved `gym/monitoring` to `gym/wrappers/monitoring`
* Add `dtype` to `Space`.
* Not using python's built-in module anymore, using `gym.logger`