Add a Workspace type.
Use utils/tar.FindFile.
Add state.backups.metadata.NewFromJSONBuffer.
Fix NewArchive.
Add a Metadata method to archive workspaces.
Factor out a basic workspace initializer function.
Remove superfluous blank lines.
Remove return arg names.
Remove a superfluous comment.
Clean up.
Fix a few doc comments.
Archive -> *Archive.
Flatten out and explain a nested if statement.
Inline the NewArchive call.
Drop the rootDir field.
Mention what a blank filename means.
NewWorkspace -> NewWorkspaceFromFilename.
NewWorkspaceFromFile -> NewWorkspaceReader.
Swap parameters in unpack().
Do not bother annotating a couple of errors.