With some further updates the print quality on the Prusa I3 B pro is now acceptable.

Updates in detail

• ESP3D for WiFi printing on an ESP8266 (in AP mode)
• Improved SaintFlint extruder (stabilized)
• J-Head v6
• Some Neopixel for showing the printer status and some more light
• Filament runout sensor for more security (not shown in the video
• Marlin 1.7 with automatic bed leveling
• Reverted to Marlin 1.6 with automatic bed leveling because of unresolved issues with Z height after auto leveling during printing. (See also https://github.com/MarlinFirmware/Marlin/issues/8831) This brought me into trouble with reproducible layer shifting when nearly reaching the end of a print. That should be a „no go“ in a stable release, but …
• …and reverted to Marlin 1.7 again. I have to apologize. It simply was a mechanical issue in my case: A broken belt pulley during update. Yesterday with Marlin 1.6 the pulley still worked. Just at the point of updating to Marlin 1.7 it BROKE INTO PIECES INSIDE. So it was not really obvious for me to find the cause of that level shifting . Sorry again for my mistake.

Marlin 1.7 comes with a whole bunch of new features which are really good improvements for your printer robots.

Most important (for me) are the features concerning the stepper motor drivers (especially TMC 2130) which allows you now to set some params for these nice Trinamic stepper motor drivers.

So:  Merry X-mas and a happy new year to all of you.
Have fun.