* Updated surface derivative algorithm to fill the return array completely * Fixed variable initialization issue causing warnings during cython compilation
5.1.1
* Fixed a bug while computing the surface derivative
5.1.0
* Added `alpha` configuration directive to `VisMPL` to control opacity of the evaluated points * Added knot refinement operation: `operations.refine_knotvector()` * Minor bug fixes and coding improvements * Documentation updates
5.0.3
* Fixed CI config which was failing to generate `geomdl.core` binaries for v5.0.2 and version bumped for user convenience
5.0.2
* Removed dependency `enum34` since it was causing problems with Python 3 * Fixed some minor bugs
5.0.1
* Fix an issue in setup.py causing generation of an incompatible wheel for Python 2.7 * conda-build configuration updates * Documentation updates