docs: improve command line usage

Closes #60

fix(folder-compare): allow opening folders in external app

fix: protect against concurrent access

chore: apply linter

Merge branch 'style/modern-toolbar'

fix(file-compare): keep destination line endings when copying lines

Closes #53

chore: fix lint issue

fix: restore settings when user clicks cancel in session dialog

Closes #49

fix: restore settings when user clicks cancel in session dialog

Closes #49

fix(folder-compare): restore expanded folders after refresh operation

Closes #45