Added mingw setup command.
Changed contingency computation and its output for continuous features.
Adapted EntropyMDL to use the new contingencies.
Re-added interface to check contingencies for single class values.
Adapted SQL contingencies.
Prevent an error with np.digitize and 0 len input.
Refactored 'Heatmap' widget.
Changed how children array is tested for valid objects.

numpy.where yields different results with numpy v1.9 and v1.8
for object arrays containing 'None'.
Fixed update time computation.
Merge pull request #101 from ales-erjavec/heatmap

Heatmap refactor
Fix sql discretization when points not given as a python list.
Merge pull request #95 from thocevar/win_setup

Added mingw setup command.
Changed how subcontingencies are combined.

i.e. by preserving maximum value from the parent cell.
Fixed a SyntaxError.
Discretize continuous data in Sieve widget.
Fix Spelling
Merge pull request #102 from jzbontar/spell

Fix Spelling
Changed heatmap rendering.

It is now rendered using a sequence of drawing primitives instead of a
large pixmap.

Also implemented adaptive contingency resampling.
Speedup heatmap painting.

(bound the drawing to the exposed area only)
Added heatmap widget icon.