utitlities updates

[larsbuntemeyer]

closes #16

[codecov-commenter]

Codecov Report

Merging #52 (db845dc) into master (cfd25f4) will increase coverage by 0.06%.
The diff coverage is 82.75%.

@@            Coverage Diff             @@
##           master      #52      +/-   ##
==========================================
+ Coverage   81.24%   81.30%   +0.06%     
==========================================
  Files          18       18              
  Lines         677      706      +29     
==========================================
+ Hits          550      574      +24     
- Misses        127      132       +5     

Flag	Coverage Δ
unittests	81.30% <82.75%> (+0.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cordex/core/tutorial.py	65.15% <ø> (ø)
cordex/core/utils.py	78.12% <80.76%> (+11.45%)	⬆️
cordex/__init__.py	100.00% <100.00%> (ø)
cordex/core/domain.py	81.96% <100.00%> (+0.19%)	⬆️