Compute center of grouped STL correctly.
Compute center of grouped STL correctly.

eyal0/OctoPrint-Slicer,DeltaMaker/OctoPrint-Slicer,kennethjiang/OctoPrint-Slicer,eyal0/OctoPrint-Slicer,kennethjiang/OctoPrint-Slicer,eyal0/OctoPrint-Slicer,DeltaMaker/OctoPrint-Slicer,kennethjiang/OctoPrint-Slicer,DeltaMaker/OctoPrint-Slicer