It adds a tool called the Tiller. When you right click on any of the blocks below, it will turn them into dirt. There are 5 varieties: wood, stone, iron, gold, and diamond. They can each be crafted by combining a shovel and a hoe of the respective material in any shape in a crafting table.
Feel free to do whatever you want with this repo. I don't really think I'll work on it more in the future.