Update loopdiagram.py

[RomanBurhenne]

When i run the loop diagrams, the inputs and outputs of the splitter and mixer branches were inversed. This way it works.

[codecov-io]

Codecov Report

Merging #149 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #149   +/-   ##
=======================================
  Coverage   60.25%   60.25%           
=======================================
  Files          51       51           
  Lines        4786     4786           
=======================================
  Hits         2884     2884           
  Misses       1902     1902

Impacted Files	Coverage Δ
eppy/useful_scripts/loopdiagram.py	80.06% <100%> (ø)	⬆️

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[santoshphilip]

@RomanBurhenne , Thanks for fixing that.
I had no idea that it was doing it wrong.

I'll review the code and merge in a few days.

[santoshphilip]

@RomanBurhenne , your update looks straightforward. The original loopdiagram.py seems broken for some reason. I need to look into that.