Release 2.2. The funny times are over.

  * Rebrand JLM into PLM (Programmer's Learning Machine)
  * Turtles: Allow for hints on segment sizes
  * Turtle.circle(): New primitive to draw circles directly.
  * New lesson turtleart on the classical Logo geometric figures
  * Upgrade our twitter4j dependency to use the new twitter API 1.1
    Twitter dropped support for the 1.0 API a while ago.
  * Drop the identi.ca spy. It does not work since the upstream move
    from status.net to pump.io, and I fail fixing it.
  * Drop our prototypal jabber chat dialog. It was not activated
    because it's not adapted: student only use it to try to cheat and
    get easy answers. A forum would be better. Students are
    authenticated, and the messages moderated (France IOI does that)
  * Build a plm-light jarfile, without scala and python dependencies.
    These langs remain usable if the deps are independently installed.
  * Specify a sain font as default to help Mac users (fix #100)