U3D exporter not working

[alemuntoni]

Given the messy and definitely non-dynamic library load system of the external u3d exporter, the call

ms.save_current_mesh('file.u3d')

fails raising a PyMeshLabException.

See #25

[ghost]

Note the workaround described in the #25 results in u3d files with no color. This could be related to #42.

[alemuntoni]

I'm happy to finally close this issue.
u3d exporter now works fine on all the platforms, both on MeshLab and PyMeshLab.
The fix will be available in the next post release and in the next releases of PyMeshLab, or you can try it by downloading and installing the last nighly artifact of the Github actions.