French translation mistakes

Attached is a patch for the French translation, which contains typos, translation inadequacies and language mistakes.
Only about 5% of the translation .ts file was reviewed, yet a fix is suggested as some mistakes are quite serious grammatical errors that cause some degree of annoyance.
Review was performed from the start of the .ts file up to a first tag, then from another tag to EOF.
Tags have been inserted (starting and ending with ** and containing "vérif") within translator comment tag data to mark start and end of review.
Source code Version: git repository master
commit ed0c57ee5a8250bceb9062beb6596756ed5bd63d