* support categorical features
* update the documentation and readme
added a test for the case where cells are supplied as a param.
* add big tests (adult test and iris)
and fixed bugs
* update transform to return numpy if original data is numpy
* added nursery test
* break loop if there is an illegal level
* Stop pruning one step before passing accuracy threshold
* adding asserts and fix DecisionTreeClassifier init
* Fix tests
Co-authored-by: abigailt <abigailt@il.ibm.com>