Extracting bits of the chart to new classes.
Switching to the Chart activity while we are working on it.
The chart must be redraw when changing the scale.
Extracting the Data render methods to a new class
Fixing the  chart colors
Moving some methods
Implementing a new Series class to hold the data for the chart.
Cleaning unused methods and fields.
Fixing the color.

Adds a paint to each series, instead of the array in the ChartRender
Clean-up and changing field scope to be more restrictive.
Changing the layout.
Dynamically create a the layout.
Using the tag field in the Chackbox to store the DataSeries.
Creating a new class to store the checkboxes
Extracting metods related to the Checkbox to its own class.
Using a method to update the series from the checkboxes.
Moving the list of checkbox to a new class, with the corresponding methods.
Creating a ChartColor class to handle the colors of the chart.
Making the ChartColor  class work as a stack of colors
Renaming the colorStack class.