Release 2.4.6

  * Worlds:
    - #329: Buggle: allow exercise to specify that Buggle's direction
      is irrelevant to world equality tests. Use it for all maze exos.
  * Pedagogical content:
    - #332, #333: French typo
    - #330: Lander.*: Make Segment usable in every exercise, even if
      they are not absolutely mandatory to solve the problem.
    - #320: indexOfValue: align the template onto the mission text
    - #334: Lander1: we are only supposed to write a method body in
      python while that's a random code chunk in other languages.
      Adapt the mission text to that fact.
    - #335: Array123: Add some tests so that testing if 3 is in the
      array is not enough to solve the problem.
    - #331: New turtle art figure, original by a student.
    - PictureMono: more space between patterns so that V are visible