Progress spys can be turned on/off through properties (plus cleanups)

- ensure that Game.i18n is setup very very soon, and don't change the
  local after initializing the whole thing.
  This really speeds up the start up.
- Add new properties to control the progress spy (twitter/identica)
- Default values of properties can now be saved to populate
  .jlm/properties (and let the user know about them).
- Not all properties are saved to disk: it makes no sense for the user
  to change JLM versions, and I'd prefer hide a bit the teacher mode,
  at least for now.

Sorry for the intermixed commit, coding during vacations lead to
strange results ;)
integrate the pancake exercises into the sorting lesson. still needs a lot of love