irt_ruby 0.2.0

IrtRuby provides implementations of the Rasch model, Two-Parameter model, and Three-Parameter model for Item Response Theory (IRT). It allows you to estimate the abilities of individuals and the difficulties, discriminations, and guessing parameters of items based on their responses to a set of items. This version adds support for multiple missing data strategies (:ignore, :treat_as_incorrect, :treat_as_correct), expanded test coverage, and improved adaptive optimization.