Prusa i3 mk2s calibration squares

Since other printable calibration squares wouldn't give me the control I needed over my calibration, I decided to publish my own version.

The Prusa i3 mk2s allows you to control bed level in multiple ways.
Firstly, the mesh bed level gets you close to correct level - This will be perfectly sufficient for beginners
Second, the live Z and the prusa test print and watching for 'squish' gets you closer to level.
Thirdly, the bed level correction allows you much finer control ( I find to with