cross platform compatibility and new documentation

Update to Wolfram mathematica version 12.0.

A full rewrite of file handling and external dependencies to allow better cross platform compatibility (Mac, Unix, and Windows).

Included more and new testing and demo data and examples.

Updated the package loader to allow monitoring of package loading and prevent pollution of the Global environment.

Updated the EPG fitting framework.

Added online documentation and website https://mfroeling.github.io/QMRITools/.