Add a script to translate navbar.mpp
Improve translation script

* Remove "open Printf", which decreases the readability of code
* Remove useless function "language_of_ISO639"
Merge remote-tracking branch 'ocaml/master' into translate-navbar
Use a translation file

Translations will be stored in translations/en_to_??.txt with the
syntax:
"english" -> "french" (* or other language, with OCaml comments *)
Translate Array of New Packages
Translate "Search" to French
Merge branch 'translate-navbar' of https://github.com/lefessan/ocaml.org