Table on chart is not centered anymore #2129
Original series are dimmed to highlight alternative (dynamic) series #2129

We also heavily simplified the chart controller to do a full refresh,
in order to keep the color/style logic on the server side. The goal
mid-term is to have so sort of cache mecanism to mitigate performance
drawback.
Could not change question type anymore

Because Doctrine2 use Identity Map pattern we cannot load an object,
modify its type, and reload it with its new type. We must be extra
careful to load it only after type changed.

This also has side effect on unit tests where we cannot keep objects
used for DB populating. So we must clear Doctrine state and be extra
careful within tests when saving objects to database.