Ms paint in minecraft

simulates MS paint in minecraft! here's how it works:
1. run the starting command (/function testpack:start)
2. fill a desired area with any concrete color with /fill (works well for map art)
3. place a carrot on a stick in your offhand, and any color dye in your main hand
4. aim your cursor at the desired concrete and right click. the concrete should turn to the color of the dye in your hand. It will lag behind your cursor some and if you move too quickly it gets choppy, so you may want to move your cursor slowly
5. right-click again to stop drawing

I'm currently working on a few things that should come in the future:

- Varying, controlled thickness
- straight line tool
- fill tool
- various shapes, such as a square, possibly including a circle (if I'm not lazy)
- the color pink- I apparently forgot to include it in the pack.