Girth-mcmc

The refactoring of the dependent package girth required several updates to the import statements. A hard requirement on girth > 0.8.0 is required for girth_mcmc > 0.5.1.

Added partial credit model to IRT models. This supports both univariate and multivariate estimation.

Univariate Signature
python
girth_model = GirthMCMC(model='PCM', model_args=(n_categories,))


Multivariate Signature
python
girth_model = GirthMCMC(model='PCM_MD', model_args=(n_categories, n_factors))

Added multidimensional graded response model as an estimation option.

Run option looks like:

python
girth_model = GirthMCMC(model='GRM_MD', model_args=(n_categories, n_factors),
options={'n_tune': 1000, 'n_samples': 1000})

Added an initial guess parameter for the multidimensional 2pl model to help with convergence.

Added as a girth_mcmc option:

python
options = {'initial_guess': True}

Added multidimensional 2PL IRT for MCMC and Variational samplers.

* Added missing data support