English typos

Just two basic typos ( classical -> classic, 'usual' would maybe be better there; Wally -> Waldo)

I didn't remove `python-pytest`, because maybe the error I had is just due to me having Ubuntu LTS and not the most recent ubuntu version. (it's not listed in the MANUAL though)

There are other changes for which I'm unsure whether to make a pull request or not, because I don't know if it's on purpose:
- In order to generate the website doc, the package `python-docutils` needs to be added (but it's not in the list of debian packages in the README)
- adding `website/*.html` and `website/license.txt` to .gitignore removes a lot of the clutter from `git status`, once the website doc is generated.