Bump version to v1.6.3
Updates to training models and tests
Fix for Makefile.ParameterizedModel
Fix particleEnergy initialization in ex_model_Cu_PF_Johnson & template
Remove use of non-standard function strtok_r()
Update Makefile regex to match := and =

Thanks to Noam Bernstein for debugging and reporting this one.
Update NEWS for v1.6.3