Completion and correction for FR translation

Hi there!

I did a global review of French translations and I did updates/corrections all around:

- syntax corrections (there is always a space before french ponctuation)
- spelling/conjugation corrections (few mistakes in general)
- rephrase some sentences and expression to sound more natural in French
- some code indentation when needed

So here is the pull request.

Please let me know if there's anything wrong so I can correct it before you pull theses changes!


Thanks a lot and regards!