[meta] Data sorting

[markov00]

This issue tracks the efforts to improve the current ability to sort data at various levels: sorting on scales, on rendering order, on legend, tooltip

• Sort DataSeries Sort DataSeries #795
• The order of the series in the tooltip does not match the legend The order of the series in the tooltip does not match the legend #303
• Enable sortIndexAccessor on SeriesSpec Enable sortIndexAccessor on SeriesSpec #160
• Allow greater control over layer rendering order Allow greater control over layer rendering order #674