egtutil: call or replace the GOLD Parser Builder CLI

This library depends on the existence of an EGT built using a) GOLD Parser GUI or b) GOLD Parser Builder. Could `egtutil` call/exec the GP CLI exe's? You would have to bundle them or use installed paths. The system must support win exe's natively, WINE, etc.

- [ ] Did GP author release source code for [GPS](http://goldparser.org/about/license.htm)?
