2.0.3

This release contains minor changes from v2 that was made public at btorboist/btmorph_v2.

1. Some minor bug fixes including some for python3 compatibility
2. New globals functions: max_EucDistance_from_root, max_pathLength_from_root, max_centrifugal_order, max_bif_angle, avg_bif_angle, avg_partition_asymmetry, avg_diameter, avg_Burke_taper, avg_tortuosity
3. New local functions: Burke_taper, tortuosity