Investigate better behavior of piezo and offsets when moving from calibration to volume

[Luigi Petrucco]

For some choices of piezo position it looks like the offset gets moved when transitioning from one modality to the other. There should probably be an option to readjust galvo offset after calibration is done? Otherwise, this needs to be 120% reliable

[Diego]

This is an extension of #37. So linking both of them together