scala file
check if RxScala is usable
Merge branch 'master' into rx
Merge branch 'master' into rx
introduce RxScala to observe card events

(first step refactoring the Observer 
to use a more maintainable framework)
migrate to scala
cleanup to better handle deck overlay disposal
Merge branch 'fixes' into rx
Merge branch 'master' into rx
Merge branch 'master' into rx
Merge branch 'fixes' into rx
Merge branch 'master' into rx
deck overlay now correctly ignores previous logged events
better maths to compute ratio of images in deck overlay
deck overlay is now resizable
deck overlay now remembers its last position and size
deck box is now a proper JFrame
restores the white curtaing over cards not anymore in the deck
test to check for message "card not found in deck"

This message was displayed even when the previous deck overlay was
closed
fix typo #307