Enhance mouse click return

[otmanon]

Currently polyscope.get_selection() in python only returns the face/cell you clicked on. It would be super useful for animation and interaction if we could additionally get just a little more info like the position on the mesh of our click!

[nmwsharp]

This should probably be improved on the C++ side too :)

I think the right way to architect this is to give the structures functions which you can call on the mouse click to get extra structure-specific info. So the psuedocode would be something like:

structure, index, pos = polyscope.get_selection()
if structure is my_ps_mesh:
  barycoords = my_ps_mesh.get_barycoords_for_selection(index, pos)

etc

[nmwsharp]

while we're at it we should also expose/bind/document get_world_ray_from_mouse_click()

[HarryRos]

This would be useful! Any plans to revisit this soon?