Python Mesh Viewer

Lots has happened, but i didn't care releasing/tagging. Until now.

Feature-wise:

• I added a new solid: truncated icosahedron (soccer ball)
• introduced 'wireframe' mode, where faces aren't displayed. You can see through.
• switch tetrahedron frequencies from 2&4 to 4&8, they are more beautiful.

Dependencies (with help of contributor François Kany, thanks!):

• updated to (and now requires) python 3
• updated to (and now requires) (py)Qt 5

Less visible, but there were the usual code factorization and bug fixes. The too common "Sphere" was renamed to the more accurate UVSphere

I wont release tarballs/zip files. The code is available at the usual place. There are links to such tarballs/zip under the download button at top-right of the tag page