Mid-process in bug fix: bug for binary classification with categorical features
* Bug: Categorical features were all treated as ordered for binary classification.  This is possible but would require the bin ordering to be determined on-the-fly after the aggregation.  Currently, the ordering is determined a priori and fixed for all splits.
* (Temp) Fix: Treat low-arity categorical features as unordered for binary classification.
* Related change: I removed most tests for isMulticlass in the code.  I instead test metadata for whether there are unordered features.
* Status: The bug may be fixed, but more testing needs to be done.

Aggregates: The same binMultiplier (for ordered vs. unordered) was applied to all features.  It is now applied on a per-feature basis.