ebnf.py, examples/FixedEBNF, examples/FlexibleEBNF: directive can now contain grammar expressions, next to regular expressions, symbols and literals

of EBNF-syntax is acceptable.

parser.py: Grammar.rollback_to__ bugfix: set last rollback location to -1 if rollback stack is empty. (How did that happen!?)

parse.py: Refactoring of Capture/Pop/Retrieve: plugabble match-functions instead of filter functions; optional_last_value() match function added; new EBNF-operator ":?" that matches empty-text but still pops the last captured value

scripts/dhparser.py - now uses XXXParser.py rather then XXXCompiler.py as default file-name for the translator

- DHParser/parse.py: resume and skip directives now jump to the reentry-point right after the match of the regular expression for re-entry

- Griechische Wörter als solche auszeichnen (damit sie später als nicht kursiv gekennzeichnet werden können)