don't play too cleaver -- don't share an entity between exercises
improve a bit the Dave error messages
port all maze exercises to scala+french
turmites are less pedagogical than mazes, as they are now
detect and correctly report a PEBAK
Port all bat.string exercises to scala
adapt the doc of major universes to french and scala
port all sorting exercises to scala+french
port baseball exercises to french+scala
port pancake exercises to french+scala
port all turtle exercises to scala