Support elliptical mask shapes

[ajshajib]

This PR adds the feature to specify elliptical masks. In the mask section of the config file, all three of "a", "b", and "angle" (see documentation of lenstronomy.Util.mask_util.mask_ellipse() for definitions) should be provided instead of "radius" for the elliptical mask to be created.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.51%. Comparing base (03e1a95) to head (c9ce44f).
Report is 17 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #46   +/-   ##
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  Coverage   99.50%   99.51%           
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  Files           8        8           
  Lines        1015     1021    +6     
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+ Hits         1010     1016    +6     
  Misses          5        5           

Files with missing lines	Coverage Δ
dolphin/processor/config.py	99.50% <100.00%> (+<0.01%)	⬆️