I also spent some time poking around the chess software on GitHub.com. The projects go beyond the basic support needed for my World Championship site and would better be addressed on my main chess blog.
10 January 2018
Continuing with Small Projects for 2018 and 'a replacement for my old PGN normalization software, which was forcibly retired last summer', I had to look no further than PGN-extract ('A Portable Game Notation Manipulator for Chess Games'). Although its output is not completely what I was looking for, it does the more important job of checking the validity of PGN files. I'll test drive it for some of the other 'Small Projects' before adopting it definitively. An overview of its functionality is available on the page PGN-extract Help file.