Set of commits to be tagged v0.20.1

Closes #316

See merge request !25

fix: open changes dir to the target file's parent directory to prevent exporting label files in current directory when tracking data file is not a descendant

Set of commits to be tagged v0.20

See merge request !24

Set of commits to be tagged 0.19.1

See merge request !23

fix: tag selector was inactive until tag filter was interacted with
fix: stepping forward or backward with arrow keys was ineffective and
triggered warnings
fix: the "edited" label was not added where expected on saving to file

Set of commits to be tagger v0.19

See merge request !22

Not sure why this is needed.

Implement issues 10 and 57

See merge request !21