Closed requested to merge 57-bugfix_chemical_system_database into master
Standardize file references files during import and export of an ogs6_obj.
File references during import (
read_in_prj()) are made always absolute and a conserved during export, except the user specifies to copy the references files into
sim_path; then relative file refs are used.
To support python script files, the class
prj_python_scripts has been added.
Following files are supported:
Closes #57 (closed), closes #58 (closed), closes #59 (closed)