[Metalab] Latest maintenance on our 3D-Printer Mendel90

[Michael Kafka]

Ohai Metalabses!

Just updgraded the firmware of our Mendel90 to Merlin_v1_Mendel90
from github. New features include:
- Support for centered arcs (instead of polygons)
- PID-regulated heatbed (instead of on-off aka "bang-bang mode")
- No acceleration/decelaration for polygons (no material build-up
  at the corners)
- Some more features...

Updated our Wiki-page with all links to new setup:
https://metalab.at/wiki/3DPrinter

Uploaded Arduino-Snapshot of the currently running firmware.

Uploaded a new slic3r.ini file.

The current setup should work for most 3D-models.
(I was almost able to print a 10cm high figurine, just some
glitches towards the end made it a failure...)

Greets,

MiKa