modular printhead for Ultimaker2 - v2.2

Modular head to aid mounting alternative heads to the Ulitimaker2

Inspired by Foehnsturm (https://www.youmagine.com/designs/ulitimaker-orig-modular-printhead-merlin-ubis) but build from scratch for the Ultimaker2.

I started with a version1 based on a mirrored baseblock of foehnsturm, but due to the asymmetrical rod placement you would lose more buildspace then necessary. I managed the get an almost symmetrical rod placement.

Some remarks;

- you can use this head with the default UM2