- added test for indirect left recursion: ilr works with DHParser but stresses python's recursion depth limit

- added `start_parser` parameter to `GrammarBase.parse` in order to allow fine grained testing of ENBF syntax descriptions;
- added `dsl.suite_outdated`
- further corrections

- potential infinite loops are now caught when running parser and an error is reported; bug fixes, tests

- Require()-Parser now yields "fatal_error" - otherwise it would be overlooked. (Parser-Error reporting in general needs to be reconsidered...!)
- testbed for MLW example optimized