Numerically stable implementation of variance calculation in core Weka classes - thanks to Benjamin Weber
Unified expression parsing framework (with compiled expressions) is now employed by filters and tools that use mathematical/logical expressions - thanks to Benjamin Weber
Developers can now specify GUI and command-line options for their Weka schemes via a new unified annotation-based mechanism
ClassConditionalProbabilities filter - replaces the value of a nominal attribute in a given instance with its probability given each of the possible class values
GUI package manager's available list now shows both packages that are not currently installed, and those installed packages for which there is a more recent version available that is compatible with the base version of Weka being used
ReplaceWithMissingValue filter - allows values to be randomly (with a user-specified probability) replaced with missing values. Useful for experimenting with methods for imputing missing values
WrapperSubsetEval can now use plugin evaluation metrics