Place seam closest to specified position

[Dreide]

In addition to the current seam positioning algorithm, I would like to have an option that allows to specify a reference position (X,Y coordinate with respect to object center), and whichever position in a perimeter loop is closest to this reference position is then chosen for the seam (à la "Choose start point closest to specific position" in Simplify3D). In addition to the reference point it might be useful to also have a parameter for jittering the seam position along the perimeter (jitter range in mm).