Provide both modular and combined recipe for Detrend?

The current recipes (e.g. see association matrix and OCA rules in !95 (merged)) has the detrend recipe split up in three parts:

mcd_img_detrend: correcting for dark and flat, per exposure (should perhaps be mcd_img_detrendintermediate)
mcd_img_background: creating a background map for all 4 or 5 exposures in a dittered observation
mcd_img_detrendfinal: correcting for the background and large scale illumination pattern (should perhaps be mcd_img_detrend)

This design is created to maximize modularity:

Reprocessing can be done per exposure, in case only one exposure of an observing block is problematic.
Processing can be parallelized automatically, thereby saving memory automatically.

The problem with this desire is that

The background has to be derived for all exposures together, and it is in the middle of the process. So the detrending has to be split up in three steps, creating a more complex workflow.
Most ESO workflows process data per template, that is, for all exposures together. This might be less efficient, but is what users expect, which is also worthy.

So it could be worthwhile to combine the above three steps into a single recipe, while also keeping the sub recipes available, perhaps as 'utility' recipes (or vice-versa).

All processing will be in DRL Functions (approximately what RecipeSteps are in MICADO-WISE), so it should be easy to design/explore several scenario's.

We will keep things as-is for now (that is, merge !95 (merged)) and revisit this after we have properly described all the DRL Functions, which has to be done anyway and will make exploring the different scenario's easier.

Edited Dec 14, 2020 by Hugo Buddelmeijer