abort after finding 20 results of any quality.
factor out suggest_typename
added X::Parameter::InvalidType with suggestions.
abort after 1000 fails, too.
actually abort after 1000 tries now.
Throw Inheritance::SelfInherit.
Merge pull request #98 from timo/levenshtein

More Levenshtein stuff:types in parameters. code cleanups. Self-Inherit error.