fixed multivalued parameter values were not correctly recorded in output MMIF

[keighrim]

fixes #214

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.66%. Comparing base (faf001f) to head (8c882b8).
Report is 4 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #215      +/-   ##
===========================================
+ Coverage    73.55%   73.66%   +0.10%     
===========================================
  Files            9        9              
  Lines          745      748       +3     
===========================================
+ Hits           548      551       +3     
  Misses         197      197              

Flag	Coverage Δ
unittests	73.66% <100.00%> (+0.10%)	⬆️

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