Move .write() into manifest_file.ManifestFileWriter
Remove .write() from Manifest. Use ManifestFileWriter directly instead
Remove initialization of dict. We don't want children to be dicts instead of Manifests
Remove Manifest.parse(). Use ManifestFileParser directly instead
Remove Manifest.from_walk(). Use ManifestDirWalker directly instead
Remove Manifest.from_tar(). Use ManifestTarWalker directly instead
Rename files and classes according to latest changes