more explicit error message
rewrite PancakeView from scratch, with rather complete mouse interaction
PancakeView: display the amount of moves
fix the translations of the lesson chooser, and translate the engine to 100%
run po4a, translation still to be updated
the baseball exercises are easier than the pancakes ones, I think
Split hanoi towers out in another lesson
Remove the meta lesson. (Fix: #2)

It was not done, seemed difficult to finish, and complicated the code
of the universes.
note the bug numbers that are fixed in the ChangeLog
try to work around the bugs in our translation infrastructure
oops, forgot again to update the po4a conf file
rename files so that different files have different names
Kill HanoiInvalidMove and use IllegalArgumentException instead, as we should
rework the Main.html of the pancakes and baseballs lessons
convert a first exercise from ArrayWorld to BatWorld
make sure that the unit test fails if we fail to load a given lesson
typo--
split the turmites out to their own lesson
partially resync the translations of missions

but I added a whole lot of new exercices, so the translations are not 100% yet.
more efficient trap against bug in the demo code of pancake exercices

I saw cases where one of the algorithms failed to sort the array, but
I didn't get enough information to fix it.