Prusa i3 Mk2/S upgrade with hybrid Mk2.5 R3 extruder

The hybrid Mk2.5 R3 extruder can be installed as part of
* a Mk2S upgrade from a Mk2, or
* standalone upgrade from a Mk2S.

**Goal**
* Upgrade to the latest Mk2.5 R2 and Mk3 R3 parts to benefit from the improvements made.
* The Mk2 PINDA probe requires adjusting Live-Z due to temperature sensitivity after long prints and when the heatbed temperature changes. Upgrading to PINDA V2 should get rid of manual Live-Z adjustments.
* Save the money for the Mk2.5 upgrade. I neither need the spr