Fix offset values on API after setting one offset
Fix offset values on API after setting one offset

Make sure to set the actual effective offsets as provided by the comm
layer (which merges incoming single offset adjustments) instead of only
setting the input, effectively nuking return of offsets set prior.

Closes #2268

Jaesin/OctoPrint,foosel/OctoPrint,foosel/OctoPrint,foosel/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint,Jaesin/OctoPrint,Jaesin/OctoPrint