Remove many useless System.out.println calls that cause the funny message described in #435 to appear
Adds a FocusListener to the text field containing the number of classes
Introducing Apache Commons Maths for statisitics.
I consequently replaces the code used in PnlAbstractCategorized to
compute equal intervals thresholds with  a better one. We now have a
Thresholds class that relies on a DescriptiveStatistics instance to
provides valuable data taht can finally be used to get the intervals.
First step toward many analysis.
We now have manual and equal intervals. Yeah. Nice.
Adds mean standard deviation classification