New in version 2.3:
- Environment now attached as "myddp" instead of "package:myddp", making searchpaths() useless

New in version 2.2:
- Vignette

New in version 2.1:
- g.data.upgrade() removed
- NAMESPACE added, making g.data.mash() and g.data.unmash() internal
- Code split into individual files
	
New in version 2.0:
- All data files stored in top-level directory, eliminate the "R" and "data" subdirectories.
- Filenames include an "@" before uppercase letters, needed for Windows.
- g.data.save() knows not to re-write promises.
- Upgrade from v1, with a backwards-compatibility mode
