added ability to skip skymatch

[rchwn]

While investigating the exposure-to-exposure and pointing-to-pointing DC flux offsets in MIRI data, I needed the ability to completely turn off the skymatch and LevelMatch steps, and to be able to turn them on individually. The current version of lv3_step.py runs skymatch by default. Suppose you've set

[parameters.lv3.jwst_parameters.skymatch]
# ...
subtract = false

i.e., you want skymatch to calculate the DC offsets between overlapping exposures, but do not want it to subtract them from the data. When skymatch is run by default, it adds the offsets to the headers, which the drizzle step adds to the data whether you like it or not. Without the ability to skip skymatch, there was no way to avoid that from happening.

Now in your config.toml file, if you set

[parameters.lv3.jwst_parameters.skymatch]
skip = true

skymatch will be skipped completely.

[thomaswilliamsastro]

Looks good, just the one comment on my side to check

[thomaswilliamsastro]

@rchwn is this still relevant? I realise it's been sitting around for ages waiting for a reply to some comments I made