Tweak to Auto Square feature

[DBS3262]

Here's the pitch...The auto squaring feature has already moved the ganged motor onto its own output. Change the config to allow access to the resolution and backlash settings. This will improve the accuracy of the machine, allowing the user to adjust for lead imperfections, and may also make it more obvious to the entry level user how auto squaring feature needs to be setup.

Here's the rationale... there is underlying problem that affects accuracy in maker grade machines utilizing lead screw transmission. The leads frequently have different resolutions. This get resolved in the config for all but the ganged axis. The slave motor takes the same steps as the master. As it should be assuming the leads are the same; However, when they're different, and they frequently are, the slave nut block will gain or lose ground based on the difference in resolution. The "lead" is the distance the nut block will move in one rotation. In most cases the difference between a set of leads in not perceptible with the naked eye. Less than the thickness of human hair for example. Unfortunately, that error is compounded with each full rotation, and the further you move the gantry from your machine home the larger that error will be. It goes largely unnoticed because the gantry always comes back to zero on both sides, and a lot of makers rarely use offsets choosing to machine in the corner the homed from. Ive experienced a 2mm difference over 1200mm of travel in a pair of leads. I then had to go through the monotonous task of testing resolutions, and trying to find the best match among my leads. Ultimately, making a compromise. Comparatively, resolution adjustment would have only taken a couple of minutes and had far better results.

[terjeio]

Adding this is, IMO, a major task - not a simple tweak.
If someone want to implement it give it a try, it is not something that I will prioritize.