Padding ignores printer's max dimensions

[Roguyt]

I've set my max print size to 340mm... But the padding actually set my baseplate to be about 355mm, which is bigger than the limit.

[redRock14]

I am having this same issue. I just made the print volume slightly smaller.

[HopperDropper]

Thank you for adding the issue to github. When I have some time I will try to address.

[ewtillman]

Just an example of the issue, I just make my build size smaller also.

[redRock14]

@Roguyt / @ewtillman - This PR holds a change to help solve the problem with the baseplates being larger than the print area. The code takes into account the padding - which was missing.

@HopperDropper - please take a look; I reformatted the code to make it a little easier to read and added a main() method.