Revert changes in PR 333

[soininen]

This reverts PR #333 as discussed there. A new PR will be opened for the changes to sort out issues.

Re spine-tools/Spine-Toolbox#2431

Checklist before merging

• [ ] Documentation (also in Toolbox repo) is up-to-date
• [ ] Release notes in Toolbox repo have been updated
• [ ] Unit tests have been added/updated accordingly
• [ ] Code has been formatted by black
• [ ] Unit tests pass

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (a97c794) 77.12% compared to head (58f12b3) 77.12%. Report is 13 commits behind head on 0.8-dev.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## 0.8-dev #343 +/- ## ======================================== Coverage 77.12% 77.12% ======================================== Files 75 75 Lines 9241 9241 Branches 1950 1950 ======================================== Hits 7127 7127 Misses 1781 1781 Partials 333 333 ```

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