next release snapshot version
fixed minor documentation copy paster
Merge branch 'master' into develop
Merge branch 'master' into develop
extract abstract base Chart traits

- trait DisplayableChart for GUI related displaying
  - also adds toPanel and toFrame to not just show but add to contents of GUIs
- trait StorableChart for saving to disk
- extract basic Chart members with type parameter for plot and use peer like scala.swing
  - extends DisplayableChart and StorableChart
- rename the Chart of RichChart to GenericRichChart
explicit return type for GenericRichChart.plot
extracted MultiplePieChart, PieChart and RingChart from ChartFactory
Comparable[_] for Series names and new converter

- now using Comparable[_] instead of String for the names of Series where possible
- adds a new converter for categorized numeric data to XYSeriesCollection
introduces XYChart
extracts XYBarChart from ChartFactory
tests plots of missing factories, too
adds converter for categorized numeric data to CategoryTableXYDataset
minor doc fix
extracts XYAreaChart from ChartFactory
extracts XYLineChart from ChartFactory
introduces CategoryChart
extracts AreaChart from ChartFactory
extracts BarChart from ChartFactory
extracts LineChart from ChartFactory and deletes the remaining stub
defines base trait for chart factories