DOC some docstrings, remove old class.
DOC some docstrings, remove old class.

amueller/pystruct,massmutual/pystruct,pystruct/pystruct,wattlebird/pystruct,amueller/pystruct,d-mittal/pystruct,massmutual/pystruct,d-mittal/pystruct,wattlebird/pystruct,pystruct/pystruct