Add new option for [General] process_new_segments_from option, 'segment_last_edit_time'. New option sets beginning of segments archiving from last edit time (or created time if it is found). Includes tests.
Looks good to me, added a comment but more like optional
Manual tests went ok, will merge.
@tsteur If there are any other issues, feel free to bring them up, I can make changes after merging.