Coobook: JumpFlood rgba8unorm

This is GameMaker Cookbook jam entry. It is Jump Flood Algorithm, which uses rgba8unorm surfaces, in one pixel stores two coordinates for both regular and reverse coordinate mapping. 

Made and tested with GameMaker version:  IDE v2023.11.1.129, Runtime v2023.11.1.160. 

More information can be found from the GitHub, which can be found here: https://github.com/HannulaTero/JFA_rgba8unorm