Added a scatter plot widget class with some code for interpolating heatmaps
Added some heatmap code to scatterplot
Removed prints from scatter plot
Merge branch 'master' into heatmap
Added to_sql() for DiscreteVariable.
Added sql versions of EqualWidth() and EqualFreq().
Merge branch 'master' into heatmap
Reverted test sql base to master version.
Modified stored procedures for discretization. Modified to_sql() in DiscreteVariable.
Added basic heatmap widget
Merge branch 'master' into heatmap, to update boxplot.
Merge branch 'master' into heatmap
Added a new Feature Constructor widget.
Assemble curves in c.

Requires a new version of qt-graph-helpers.
Added globals for Feature constructor expressions.
Fixed freevars calls.
Added Naive Bayes learner widget.
Added Predictions widget.
Widget Data Info no longer requires psycogp2
Fixed in CrossValidation and testing.Results
Changed/Added unit tests for testing.CrossValidation
Renamed MajorityLearner to MajorityFitter