Allow tooltips on toolButtons.
Fix a contingency indexing bug.

contingency['iris', 'iris'] worked, while contingency['iris']['iris']
failed. The second form of indexing is used in parallel coordinates
widget.
Copy files from orange2 with applied 2to3.
Fixed inconsistent use of tabs and spaces.
Copied files from orange2 & 2to3.
Fix imports, tabs and spaces.
Copy scaling from orange2.
Fix errors.
Code style.
Copy from Orange2
Fix errors.
Removed code with unsatisfied dependencies.
(barely) working widget.
More fixes.
Code style, underscore instead of camelCase.
Fix a bug - show all axes.
Refactoring.
Remove stuff I do not plan to support.
Remove parameter that is never used.
Pass bool instead of int.