Metadata versions
=================

KnowledgeTree can keep a historic view of both the physical document and
the associated metadata.

Version creation
----------------
Metadata versions need to occur when:
- A new physical document is added
- Metadata is changed

Database effects
----------------
Metadata versions are stored in the standard documents table, with the
document status set to STATUS_HISTORY (6).  Metadata versions are copies
of the document table currently, and all associated generic and
type-specific metadata.  Each metadata version has its own metadata
version number (metadata_version, getMetadataVersion()).

This configuration makes searches much easier.

Interface changes
-----------------
Metadata versions are listed in the document detail view under "Metadata
Versions".  When selected, the document detail view is updated to place
the metadata version on the right-hand side of the view, allowing
comparison.
