Engine update, performance improvements

Humanity Must Perish v1.1 has now been released. The changes may not be noticeable on most systems, since visual novels aren't exactly taxing on a modern computer, but this update is mostly about performance improvements.

The engine on which HMP runs has been updated. Portions of the code have been rewritten, and animations should now be smoother and more consistent.

If you run into any issues with the update, please either reply to this announcement or reach out to me at https://twitter.com/ZetsubouGames