Input File Revamp

[rdoddanavar]

• https://stackoverflow.com/questions/1186789/what-is-the-best-way-to-call-a-script-from-another-script
• https://stackoverflow.com/questions/436198/what-is-an-alternative-to-execfile-in-python-3

[rdoddanavar]

Focus on making input simple, remove input CPP structures; addresses items in reopened #6