Tag to be used with the master branch of atlas/athena. Update(s) since 2.0.98: - (Slightly) Updated the GeoModel version, and dropped the "old" GeoModel find-modules; - Fixed Findnlohmann_json.cmake to add the JSON include directory correctly to $ROOT_INCLUDE_PATH; - Updated CLHEP to version CLHEP_2_4_1_3_atl01.