Consider producing cross-channel signal analysis in multiple forms

[vreuter]

Right now, the cross-channel signal analysis output is one file per channel. This preserve the desirable property of having a single row per spot/ROI (either regional or locus-specific): one row, one ROI.

However, this has at least two downsides:

• Information duplication: the original ROI record is repeated identically in each channel's output file.
• Parallel collections: concomitantly, there's a sort of maintenance of parallel collections going on; specifically, the values/measurements which are conceptually related (pixel value statistics in a ROI) are split into separate, parallel collections and must be brought back together in order to do any sort of joint analysis.

Idea in principle: emit these statistics/measurements also in joint form (not separate, parallel collection).

Implementation proposal: decide on a general ROI key, and have that mapped to additional ROI fields and to a collection (mapping) from channel to measurements/statistics.