Morph-kgc

- Added `safe_percent_encoding` option to avoid percent encoding of specific characters.
- The default value of `clean_output_dir` has changed to *false*.
- Several changes regarding **hierarchical** data sources (JSON and XML):
- Migration from `lxml` to `elementpath` library. This entails that from this version, Morph-KGC uses **XPath 2.0**.
- References in the mapping rules can access elements in lower levels of the tree (e.g. *author.name* in JSONPath or *author/name* in XPath).
- Minor bugs fixed.

- Automatic inference of file data format. It is no longer needed to specify the data format in the configuration file.
- Handling [escape sequences](https://www.w3.org/TR/turtle/#sec-escapes).

- Full compatibility for _JSONPath_ supported.
- Full compatibility for _XPath_ supported.
- Minor bugs fixed.

- No longer generates `xsd:string` data types, as it is equivalent to not specifying a data type.
- Fixed bug where integer RDB columns with _NULLs_ where generating float values 35.

- Updated dependencies versions.
- Minor bugs fixed.

- Data type inference for Oracle.
- Fixed bug with `rr:sqlQuery` generating _NULL_ values, 35.
- Fixed bug for JSON.