TrackChanges: reset in combination with matches is buggy

problem:

• User A opens a segment with some content and a TrackChange-INS from User B.
• User A resets the segment to its initial content.
• User A takes over a LanguageResource-match => ALL of the deleted content is marked as deleted by User A AND inserted by User B.

solution:

• Compare all users of the TrackChange-history before merging the DEL-node, not just the latest one.