properly check whether the tested exercises are ported to scala
when the brush is down when changing its color, mark the ground
We can 'save as' even if the map was not modified
reorg of exercises that apply methods (and decompositions)

- a set of 3 exercises were compacted in two only to not get boring
- 2 nice new exercises (package methods/flowerpot) were added
port all new training exercises on methods to scala and python
convert all bat exercises to scala