test/ebnf.py: `\~` is now substituted by mangled whitespace in regular expressions for _skip and _resume

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

- configuration presets refactored in order support multiprocessing start methods "spawn" and "fork-server"

- DHParser/stringview.py, log.py: better object representation