* `NURBS.ctrlptsw` now returns a tuple * Algorithm and compatibility updates to surface grid generator * Add more tests
4.0b6
* Fixed an issue which causes figure display problems during rendering curves and surfaces in `Multi`-type classes * Coding improvements in `utilities` module * Added more tests, increasing the code coverage to 47%
4.0b5
* New feature: Exporting plots as image files * Documentation: Added [exporting plots](http://nurbs-python.readthedocs.io/en/latest/visualization_export.html) section with code examples * Documentation: Updated [load-save](http://nurbs-python.readthedocs.io/en/latest/load_save.html) section with some code examples
4.0b4
* Bug fix: The sample generator function was not considering the starting value