Datalad-revolution

This release brings a complete reimplementation of the essential metadata handling commands:

- `rev-extract-metadata` -- real-only command that drives any metadata extractor on a single dataset
- `rev-aggregate-metadata` -- simplified, faster, more clever replacement for `aggregate-metadata` (figures out when to do things, and supports detection of extractor (configuration) changes
- `query-metadata` -- report any aggregated metadata from a single dataset (but on as many datasets/files as have been aggregated into the queried dataset

Both `rev-extract-metadata` and `query-metadata` are capable of reporting a single JSON-LD graph, with all the JSON-LD-type metadata found.

Apart from metadata, the `rev-diff` command has made its way into Datalad core (as `diff`), and has been removed from this package (a shim stays in place).

Most commands have successfully migrated to DataLad proper. Import shims have been put in place.

- Prevent subdataset creation in conflict with superdataset content

Re-release 0.8.0 binaries to PyPi with stale bytecode removed. No change in any functionality otherwise.

This release now longer provides the enhanced Repo/Dataset base classes. They have been merge into core DataLad. Dependencies are adjusted accordingly, no breakage of dependent code is to be expected.

- Various fixes
- Various minor API changes (renames) to ease merge of base functionality into datalad proper
- New metadata extractor for custom JSON-LD compliant metadata.