Verthash datafile generation written in Python

This project could use a native verthash datafile generation written in Python.  Currently, it runs a separate binary to generate verthash.dat which is far from ideal.

Examples of verthash generation in C++ and Go:
https://github.com/vertcoin-project/vertcoin-core/blob/master/src/crypto/verthash_datfile.cpp
https://github.com/sencha-dev/powkit/blob/master/verthash/graph.go