Handle multi target inputs

[VesnaT]

• Show error message when input data (or model domain) had more than one target
• Fixes Inspection and ICE don't work with newer scikit-lern #67

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (9da17ff) 93.51% compared to head (65721d6) 93.55%.
Report is 6 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #69      +/-   ##
==========================================
+ Coverage   93.51%   93.55%   +0.03%     
==========================================
  Files          16       16              
  Lines        5029     5057      +28     
==========================================
+ Hits         4703     4731      +28     
  Misses        326      326              

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