Psychometric mixture models based on 'flexmix' infrastructure. At the moment Rasch mixture models
with different parameterizations of the score distribution (saturated vs. mean/variance specification),
Bradley-Terry mixture models, and MPT mixture models are implemented. These mixture models can be estimated
with or without concomitant variables. See vignette('raschmix', package = 'psychomix') for details on the
Rasch mixture models.