Add unitcellTranslationalCoords as class attribute

[vpasumarthi]

https://github.com/vpasumarthi/KineticModel/blob/2a0a0057f36d32befc003d04c2eee6fba2426d3c/SourceCode/KineticModel.py#L191

Currently unitcellTranslationalCoords is neighbor class attribute. Check if the same quantity can be imported from material class attributes.