optimized feature selector by George Forman
refactor parallel map usage
use ParallelHelper in Preprocessor
remove parallel gem dependency, specs
bump version to 0.2.0.pre
fix forman selector, add specs
fix that renaming on this place too
only count a feature once per bag
add word selection setting to forman
refactored selectors
Merge branch 'forman_selector'
add stemming as option to the preprocessor
bump version