Add methods in mathex.py
ndarray_get_index_by_interval
ndarray_categorize_data
np_get_index
ndarray_mask_equal
ndarray_arraylist_equal_shape
DataFrame_from_flatten_arraydict
modification in gnc.py
remove:
    Add_Flat_Vars_to_DataFrame
add:
    Add_Vars_to_Dict
Merge remote-tracking branch 'origin/master'