Improvement: Clean up src folder

[spenke91]

Closes #1866

Describe your changes here:

Here is my suggestion for renaming the considered files:

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.95%. Comparing base (f2d3ccd) to head (d19d8ed).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2142   +/-   ##
=======================================
  Coverage   77.95%   77.95%           
=======================================
  Files         113      113           
  Lines       19087    19087           
=======================================
  Hits        14880    14880           
  Misses       4207     4207           

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[holke]

Great change and a good clean up of our code :)

I would suggest to put the eclass files into their own folder "eclass" and not into the element folder.
"element" should be reserved for SFC related low-level implementations and "eclass" is more related to the cmesh.

[spenke91]

I would suggest to put the eclass files into their own folder "eclass" and not into the element folder. "element" should be reserved for SFC related low-level implementations and "eclass" is more related to the cmesh.

Yes, the eclass was the part I was most unsure about, so sounds good to me! I changed it as you suggested 👍

[holke]

Really great clean up :)

Please resolve the merge conflicts, then we can merge.