Update fork

[chhtz]

There seems to be a slightly more up-to-date fork of libply here: https://github.com/4og/libply. It switched from autotools to CMake (although it uses some slightly weird own implementation of FindBoost), and it got rid of the std::tr1:: usages (replacing it by the corresponding c++11 headers/functions).
Unfortunately, it does not seem to build with g++6, either (cf: #1)

The original link to http://people.cs.kuleuven.be/~ares.lagae/libply/ appears not to be available anymore.

There is an archive-link however: https://web.archive.org/web/20170211235550/https://people.cs.kuleuven.be/~ares.lagae/libply/ -- so it seems there never was an official update, by the original author.