Handle unknown values in logistic regression.
Added base_value translation when reducing a variable.
Added 'get_distributions_for_columns' function.
Added class treatment options to Continuizer widget.
Prune superfluous array creation.
Fixed FloatSlider's missing signal.
Fixed valuecount's running equality check for NaNs.
Fixed attr/class/meta column tests in _compute_basic_stats.
Fixed 'Table._filter_is_defined'.
Added 'Impute' widget.
Allow empty slices (to copy/update sql tables).
Merge branch 'master' of github.com:biolab/orange3 into mosaic