Added difficulty setting!

Very small update, adds a difficulty setting so that if you are having trouble, you can find the right difficulty for you!  If you have already started playing, you can go to the settings menu to change your difficulty.  If you haven't started playing yet, you should be prompted to choose your difficulty when you first begin!

The Harder difficulty is the same as the previous version of the game, Normal and Easier have had enemy health nerfed by 80% and 60% respectively, and so if you were having fun and want to keep playing, sticking to Harder difficulty would be the way to go!