GTAP-E Validation

This release describes the project as it was when it was solely for validating GTAP-E. This release reflects the draft of the paper as of today (2018-4-18).

I chose to publish this as a "release", as the next step in this project will take it in a different direction by generalizing it. I'm going to rename the project and then add additional functionality to it for modifying the initial database, in order to generalize the use of Python to automate GTAP models.