Brings improvements

Balance
- No more empty weight
- Left weight should not go to right scale
- Reducing the size of half

Morpion
- Correction de l'évaluation des lignes

Train
- Add <1 and <0.1 options
Signed-off-by: Didier Bathily <didier.bathily@njin.fr>

Mouse events handlers works for UB types and for some Qt types. Mouse events for other items hanlded by QGraphicsView.
It solves some troubles with items selections and fixes Sankore-721.

Fixed some related issues.

 Interact with item bug with eraser