sort pie charts by size of slice

[devvmh]

This is a pretty simple change, but it makes all pie charts look nicer out of the box.

If this should be configurable instead, I could take a crack at building the configuration option. I just can't imagine where that configuration should go. Is it a button? Is it in the serialized view?

This seems to be a more sensible default than the old behaviour though.

[jjmontesl]

To me this would be a view option in the view menu (with a corresponding entry in the serialized view). Let's merge as it is for now.