Updated the copyright years, auto-recognition
Updated the copyright years, auto-recognition

Replacing our old 3-clause BSD license with one GitHub automatically
recognises, hopefully making it easier for people to understand our
licensing. No substantive change, I thought this was recognised when
first added.

Signed-off-by: Marcus D. Hanwell <cf7042e2e8eee958b5bcde1ae2cbefef82efc184@kitware.com>

ghutchis/avogadrolibs,ghutchis/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,ghutchis/avogadrolibs,ghutchis/avogadrolibs,ghutchis/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs