ENH explicit initialization + deallocate memory
ENH remove unused variables + Use better variable name + xrange -> range
ENH simplify code path
TST imporve tree equality assertion
ENH use appropriate type ofr index
ENH explicit name
ENH extract binary search from code
ENH use memcopy
predict & predict_proba can take sparse data, they are not densyfied internally anymore
Null initialization of feature_to_color and feature_values
Modified the predict and predic_proba function to hanlde sparse input
flake8ed test_tree, and tree.py
Changed random forests to support sparsity
WIP start rationalizing positive and negative value indexing
ENH better variable name
ENH faster binary search
ENH more descriptive variable nmae
ENH remove duplicated variable (current_col => Xf)
ENH get rid of tmp_indices
ENH make a function for nnz value extraction