Merge GAIA BP RP data

[Chamani8]

New script to merge Gaia BP RP data into format that is compatible to be used with measure_extinction package. This script assumes that the original Gaia BP RP data for all the stars are stored in a single fits file, then follows the generic method to merge the BP and RP fluxes for each star.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.92%. Comparing base (fa2ac69) to head (97c1acd).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #174   +/-   ##
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  Coverage   47.92%   47.92%           
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  Files           7        7           
  Lines        1932     1932           
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  Hits          926      926           
  Misses       1006     1006           

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[karllark]

Please fix the codestyle error.

[karllark]

I'm wondering what the plot looks like with this code. If I read things right, the code is going to create many fits files, two for each star. The versions of this code for other data are for a single star, so the plot then is straightforward to understand. Is the plot a lot of spectra? If so, does it make sense to include the plotting code?

[Chamani8]

The plotting code is meant to make one plot per star, and save it rather than show it when the script is run. You are correct then it makes two plots per star, one for BP and another for RP, but it does not make overplot the stars in a single figure, rather it makes a separate plot for each star. I think the plotting is still useful to go back and check what the script did.