Add SphereMesh and EllipsoidMesh classes.
Use new ellipsoid/sphere generation in demo and add unit tests.
Add simple interface to build unstructured meshes of ellipses.
Check that CGAL is available in demo for generating unstructured ellipse meshes.
Add ellipse and ellipspoid meshes to demo.
Documentation updates for mesh generation.
Get doc tests to pass.
Merge branch 'garth/sphere-circle-meshes'