a magnet based probe

This is a total reshape of Unklicky, since microswitch is no longer used.

It is a compact design with just two sets of magnets, still providing sufficient stability.

It requires higher force for operating, so it's possible to touch the z-endstop directly with the probe pin.

Unfortunately the Klicky parts are not compatible with this model. 

BOM:

• 4x 6x2.6mm round magnet 
• 1x 6x2.5(~3)mm, hole 3mm, round magnet
• 1x 3x2mm round magnet
• 1x M3x12 SHCS (carbon steel screw with strong magnetic required,  partially threaded screw preferred)
• 1x M3x5x4mm heat set insert
• 2x M3x16 SHCS (for Stealthburner toolhead mount)
• 1x 6x3mm round magnet (for side dock)
• 2x M3x16 SHCS (for side dock)
• 2x M3x5x4mm heat set insert (for side dock)
• 1x M5x10 BHCS (for side dock mount)
• 1x M5x30 BHCS (for side dock mount)

Installation:

Note that you'll need to sand the pin for a smooth surface.

Ensure these two magnets repel each other.

Offset values for Stealthburner:

(please verify these values before printing, they may need modifications for your case)

x_offset: 27

y_offset: 0

z_offset: 11.2

switch_offset: 0.02 (for automatic z offset calculation)

Resources:

Unklicky: https://github.com/majarspeed/Unklicky

Klicky: https://github.com/jlas1/Klicky-Probe

auto z offset: https://github.com/protoloft/klipper_z_calibration