Sum over fine energy bins by default

[grazwegian]

When the energy bins are fine the proportional discrepancy introduced by the ELUT can be significant. During the fine bin campaign 2023-07-31 to 2023-11-04 three energy bins between 6.3 and 7.3 keV were determined (6.3 - 6.56, 6.56 - 6.8. and 6.8- 7.3) to better investigate the Iron and Nickel lines in this region. For more standard spectroscopy to minimise the ELUT correction error it is more convenient to combine these bins into a single 6.3 - 7.3 bin. This would be the default mode for the stx_convert routines with the full energy resolution data being available through a keyword.

[ennosigaeus]

This was discussed in today's weekly telco:
Ewan has started this work. A branch has already been started with modification, but it will require some extra work to be finished. Ideally, it is somebody from the Polish team (e.g., Arun).

Branch: https://github.com/grazwegian/STIX-GSW/tree/sum-fine-bins

Säm will contact Arun, and Ewan will be there to help if needed.