Feature: ability to compute distances between locus-specific spots from different trace IDs

[vreuter]

Some different regional barcodes may be in close proximity and we'd like to compute distance b/w locus-specific spots identified within the corresponding ROIs, even though that may mean computing distance b/w a pair of spots from different regional barcodes.

• [ ] add config hook for maximum distance at which regional spots may be considered close for this permission (to license distance computation b/w pairs of locus-specific probes from different regional probes)
• [ ] flag these pairs somehow?
• [ ] decide about typical value for this max distance threshold

@TLSteinacker

[vreuter]

From discussion w/ @TLSteinacker , need to be aware of cases in which one sister's regional barcode yields spots that are considerably brighter than that of the other sister. In this case, we could end up losing some data. To counteract this, we could consider trying to expand the ROI to capture the hypothetical dimmer regional spot for the sister which should be nearby.

[vreuter]

Superseded by #279