feat(charts): keep selected categories when changing periods in charts by category (fix #692)
This fixes the issue where the categories do not remain hidden (after the user chose to hide them) after a period change.
Unfortunately this is quite heavy: I could not find another way than storing in state the list of hidden categories and thus re-rendering every category chart when a legend item is toggled.
Also pie charts cannot be configured with hidden series, this needs to be done once the chart is created…