DWDS/Dialing Concordance Code

- user data void *m_User (for perl wrappers)
- stringification method toString()
- json stringification methods toJson(), jsonClass(), jsonData()
- object substructure methods Children(), DisownChildren(), Descendants(), Traverse(), TraverseConst()
* for future use in perl-wrappers (better reference counting)
+ re-factored CQuery, CQFilter, CQueryOptions, CQueryCompiler into ddcObject