Pie chart of continents should always display all continents (and no "others" element) #1543

In the special case of displaying continents, it makes no sense to hide three out of six continents. A pie chart should be able to display six or seven elements. In the attached example there is no reason to group South America (>5%) into the "others" element.

This conflicts with #1118, I think.

Keywords: pie,chart

Attachment:
pie-charts.png

Sorry, the ticket I meant was #1118, not #804

(In [2846]) Fixes #1543
increasing pie + vertical bar charts to show 6 elements