Update lunar lander tutorial with v0.5.0 features

Description

We update the tutorial so that it is in line with the new tutorial structure in #291. We also expand the features demonstrated in this tutorial.

Depends on #291 and #295

moviepy woes

Update: It turns out this was all due to the decorator module not being loaded properly; see https://github.com/Zulko/moviepy/issues/1625 -- we just have to reload decorator so that moviepy imports it correctly.

One notable issue was that the tutorial needed ffmpeg to be installed in order to generate videos; this happens because the new Gymansium depends on moviepy for video recording, which in turn depends on ffmpeg. This is not a problem for Colab users as ffmpeg is already installed there, but local users may encounter frustration -- the video generation happens after the run, so they may do the run, wait for 2 hours, and then see that the videos fail. The steps that fail are as follows:

Create a Conda environment with Python 3.7 and activate it.
Install the package with pip install -e .[visualize]
Install jupyterlab with pip install jupyterlab
Start jupyterlab and run the notebook.

Leads to error on first display_video line with message looking like:

     86             '-s', '%dx%d' % (size[0], size[1]),
     87             '-pix_fmt', 'rgba' if withmask else 'rgb24',
---> 88             '-r', '%.02f' % fps,
     89             '-an', '-i', '-'
     90         ]

TypeError: must be real number, not NoneType

It appears that if you re-run the notebook without changing anything, everything then works, perhaps because imageio_ffmpeg has had time to load its ffmpeg executable (under the hood moviepy uses imageio_ffmpeg to get ffmpeg).

I tried to see if we could overcome this by loading the ffmpeg executable early on, but it did not work:

import imageio_ffmpeg
imageio_ffmpeg.get_ffmpeg_exe()

I also tried installing moviepy beforehand, so if it is installed before running the notebook, everything works.

TODO

[x] Update tutorial to reference the lunar lander MAE tutorial
[x] Log QD score in tutorial
[x] Add CQD score to tutorial -> doesn't fit
[x] Cut back on notes
[x] Link to documentation for features when mentioning them
[x] Show best_elite
[x] Explain elites_with_measures
[x] Explain two-stage improvement ranking
[x] Make sure the imports are still correct after changes
[x] Add QD score offset (find paper which explains offsets)
[x] Replace all latest links with stable (links will be broken but it's okay)
[x] Rerun the tutorial to have consistent images

Questions

Status

[x] I have read the guidelines in CONTRIBUTING.md
[x] I have formatted my code using yapf
[x] I have tested my code by running pytest
[x] I have linted my code with pylint
[x] I have added a one-line description of my change to the changelog in HISTORY.md
[x] This PR is ready to go

icaros-usc / pyribs