Stellar model grid data for isochrones Python package

These are the data files that get downloaded by the "isochrones" Python package.  "mist.tgz" and "dartmouth.tgz" contain stellar model grid data for the MIST and Dartmouth stellar models (http://waps.cfa.harvard.edu/MIST/ and http://stellar.dartmouth.edu/models/).  "dartmouth.tri" is the precomputed Delaunay triangulation for the Dartmouth models (the MIST models are too big to use the triangulation-based interpolation method).

***Note***

For the dartmouth grids here, this zenodo repository should now be used: https://zenodo.org/record/1002927.