The autoconversion of logical-value columns should not prefer logical

[numeredev]

SUMMARY

Implements necessary changes for #81

Reviewers: @numere-org/maintainers

IMPLEMENTATION

• Implementation: Changed the preference to value columns and extracted the detection code into a static helper function.
• Implementation test: Created a file with mixed logical and value values. The import was successful, all logical values were converted to 0 and 1.

DOCUMENTATION

• [x] ChangesLog updated
• [x] Code changes commented
• Documentation articles:
  • [ ] corresponding documentation articles updated
  • [ ] new documentation articles created
  • [x] not needed
• Language files:
  • [ ] corresponding language files updated
  • [x] not needed

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TESTS BY REVIEWERS

• [x] Added to the automatic SW tests
• [x] Tested manually