The files are a bit of a mess, so I didn't include them originally. But I extracted the relevant parts and added a new Resources section at the bottom where they are included.

util.hpp: https://gist.github.com/pingpoli/160c57af2a64bdda047834ac6eddcfd6

timeutil.hpp: https://gist.github.com/pingpoli/6079472bd0105c39705ab49820a65ae1