Modifications for 3mm to 1.75mm conversion

I've finished switching from 3mm to 1.75mm filament.

The big changes:
1) I'm using a 1.75mm Ubi's rather than a 3mm JHead MkIV. The Ubi's is
about 10mm longer and has other small geometry differences (e.g. groove
mount) which required modifications across the board.

2) I'm using an M5-.8 push-fit from SeeMeCNC now. But I had to generate
the thread model at 5.4mm to account for quirks on my printrbot.

Other fixes:
1) zprobe_clamp uses a nyloc nut - it tended to vibrate loose over time
before
Latest kisslicer settings

For 1.75mm PLA