NURBS-Python (geomdl) v4.0.1

• Bug fix: Use six package to maintain Python 2 and 3 interoperability for meta classes
• Bug fix: Updated order property for curves and order_u, order_v, delta properties for surfaces by removing excess conditional checks from their setters
• Updated error messages
• Updated documentation
• Updated tests
• Various minor updates and bug fixes

Please see the documentation for more details on the new and updated features.

For installation options, please see the following documentation page: http://nurbs-python.readthedocs.io/en/latest/install.html