refs #13 Refactor DecisionTree and StuntzHuntz.

DecisionTree is now a component of StuntzHuntz.
Merge branch 'enhancement/13_matlab_to_cpp' of github.com:osurdml/treemower into enhancement/13_matlab_to_cpp

Resolved:
	src/stuntzhuntz.cpp
refs #13 Make DecisionTree a superclass of StuntzHuntz.