Stripy v2.0

This release contains the following new features:

• Voronoi diagram (see Cartesian example and Spherical example)
• Interpolation / gradients / smoothing with spline tension (see Cartesian example and Spherical example)
• New elliptical equispaced mesh in cartesian_meshes
• Central area node weights for any mesh
• Efficient evaluation of second derivatives on a Cartesian mesh
• Better docstrings
• LGPLv3 license
• Other small bug fixes

This release is compatible with conda and can be installed by conda install -c underworldcode stripy

[Edit - version numbering fixed]