GraphMatch fix

[liunicholas6]

Some subgraphs are being incorrectly flagged as isomorphic in GraphMatch. This is due to the fact that checking that all edges are individually isomorphic between two graphs is not a sufficient condition in GraphMatch. The code in the commit PR maintains a map of vertices throughout GraphMatch to address the issue.

I have example failing tests on the failed-tests branch of the fork (the commands run are in failed-tests.txt and the bad outputs are at tris.txt and hexes.txt).

Corrected outputs are on the passed-tests branch on the fork.