trace.py: refactoring: resume notices functionality added to trace.py (like history tracking not yet removed from aprse.py)

- Überschüssige Spation nach Anker-Elimination beseitigt (weitere Einheitentests für ähnliche denkbare Fälle nötig...)

parse.py: removed overriding _apply()-methods of parser objects in favor of the overridable sub_parsers()-method

parse.py: added optional resume and skip notices to debug/track reentry-points after errors occurred

parse.py: reentry_point() can now restrict its search to a limited search window, rather than the whole document.