Add y-cruncher

y-cruncher is a software to calculate math constants(i.e. pi, sqrt(2) and so on)
It's been used to create the new world record of pi digits (300 trillion digits), and widely used to test the performance of PC.

Webpage: https://www.numberworld.org/y-cruncher/
Source code: https://github.com/Mysticial/y-cruncher
Version history: https://www.numberworld.org/y-cruncher/version_history.html