Added
- Utility for supressing pystan (or other compiled function) output. This
addition is motivated by [an rpbp issue](https://github.com/dieterich-lab/rp-bp/issues/10),
and the solution is basically [copied from facebook's prophet](https://github.com/facebook/prophet/issues/223#issuecomment-326455744).
- DatasetManager class to ease reading data and preparing it for sklearn
- Several changes to the ML helper transformers to make working with mixed
data sets (that is, those with categorical and numerical features) easier
- Several sklearn transformers which are robust to missing data and preserve
the missing data (i.e., `np.nan`s) so downstream processing can account for
the missing values appropriately.
- Utilities for working with text (`misc.nlp_utils`,
`misc.incremental_count_vectorizer`)