-----------------
- Change rest-of-line strings to include all characters given, including
leading and trailing quotes and spaces.
- The *NestedText* top-level is no longer restricted to only dictionaries
and lists. The top-level can now also be a single string.
- :func:`loads` now returns *None* when given an empty *NestedText* document.
- Change :exc:`NestedTextError` attribute names to make them more consistent
with those used by JSON package.
- Added *NestedTextError.get_extended_codicil*.