added more attributes to nuclide
Created by: Shimwell
While I was having a look around the internal structure of openmc I noticed that there is some nice attributes in the openmc.data.py file. This PR is aimed at accessing some of these attributes through the openmc.Nuclide class.
Openmc.Nuclide can be created with a string such as 'U235' and currently has just a single attribute that returns the name. I was wondering if adding some additional attributes might be nice as they allow users to conveniently access information on the nuclide such as number of protons, neutrons, nucleons and the element name.
Thanks for considering this small PR, if the idea is welcome I am happy to add some more attributes to the openmc.element class in another PR.
I also added a few unit tests to check the expected attributes are returned.