Implement a 'proper' histogram plot

[iwbnwif]

The current histogram plots do not really produce histograms, but are more or less an XY variation of a bar plot.

Histograms should be based on a category concept, and therefore use a single dimension dataset with the 'bin' ranges associated with categories.

To do this, the category set (known as the base series) in a UniDataSet should contain a HistoBin data type, with the following 3 members: double RangeLowValue double RangeHighValue wxString Name

Any value interpretation (see value interpretation description) that falls between RangeLowValue and RangeHighValue gets aggregated to the appropriate bin.

The chart is then plotted as a bar plot with the value of each category being the number of data points in that category's bin.