Use flexible output name

[mdecleir]

Small PR to make the naming of the average extinction curve a little more flexible.
This is to make the script compatible with scripts in the spex_nir_extinction repo.

[codecov-commenter]

Codecov Report

Merging #94 (7f3486e) into master (520751a) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #94      +/-   ##
==========================================
+ Coverage   46.37%   46.45%   +0.07%     
==========================================
  Files          19       19              
  Lines        2536     2536              
==========================================
+ Hits         1176     1178       +2     
+ Misses       1360     1358       -2     

Impacted Files	Coverage Δ
measure_extinction/utils/calc_ext.py	71.42% <100.00%> (ø)
measure_extinction/extdata.py	64.09% <0.00%> (+0.35%)	⬆️

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[karllark]

Awesome update. Especially the docs!