docs: update online doc with new environments

[clement-bonnet]

fixes #155

• add new environments to the online doc
• update RobotWarehouse and Tetris PNGs and GIFs
• display all 18 GIFs in the readme

[clement-bonnet]

Here is the current look of the readme

[TristanKalloniatis]

Here is the current look of the readme

Looks good, a couple quick questions:

1. Some of the renderings look pretty similar, especially cleaner and maze. So in this view looks slightly odd IMO.
2. I don't get the ordering in this collage

[TristanKalloniatis]

Is it purely alphabetical, ie not separated by env "type"? I ask because this is different from the order on the repo front page (in the table I mean)

[clement-bonnet]

Here is the current look of the readme

Looks good, a couple quick questions:

1. Some of the renderings look pretty similar, especially cleaner and maze. So in this view looks slightly odd IMO.
2. I don't get the ordering in this collage

1. Maze and Cleaner are under the hood using the same viewer abstraction, therefore they look similar indeed. I think it is even a good thing since you can show that things are easy to share. Either way, it is better to have all 18 environments that a selection that could make people think that only a few numbers of environments are implemented.
2. Ordering is by alphabetic order (to mimic the paper).