More jshint errors

[outoftime]

https://trello.com/c/JuoHRCmt/93-more-jshint-errors

Go through the jshint code and audit all error message it is able to generate. Integrate all that are useful to us.

The mappings for jshint errors live here; the validation tests live here (though check the other language validation tests, which are more robust, for inspiration). The translation file that generates the error messages is here.