Version 0.3.0

Version 0.3.0 brings "blocks" to metadata. These are very extensible dictionary/object metadata containers that can be purpose-built and controlled separately, to avoid issues with muddling different schemas in the same level. These blocks replace the old namespaces, and can be accessed in Search similarly: The field "mdf-title" is now the "title" field of the "mdf" block, as in "metadata["mdf"]["title"]" (Python) or "mdf.title" (Globus Search). This is a breaking change, necessitating a new "major" (pre-alpha) version. The validator has also been updated with further enhancements, mostly relating to the new schema.