Make Yuletide Galvan's drills cycle colors#814

It’d be cool if Yuletide Galvan’s drills had a chance of being one of the four colors on his back.

Each time a drill is placed, it could be one of the colors on Galvan’s back, and then proceed to the next color the next time another drill is placed.

The colors could cycle between Red, Yellow, Green, and Blue, instead of just being Red all the time. Alternatively, the color could be randomized between one of the four each time a drill is placed.