Experimental module for filled gauges
Maps: Finished colorAxis logic with multiple stops.
Refactored the assignment of values to parallel arrays to make it easier to override with multidimensional series types.
Maps: Removed point.y option and instead use point.value.
Maps: Got heatmap demo up and running again. Fixed ColorAxis for inverted charts.
Fixed issue with flags on the last point dropping down to the X axis when the main series enters data grouping. Closes #2374.