borg < 2:
obj = encrypted(compressed(data))
borg 2:
obj = enc_meta_len32 + encrypted(msgpacked(meta)) + encrypted(compressed(data))
handle compr / decompr in repoobj
move the assert_id call from decrypt to RepoObj.parse
also:
- for AEADKeyBase, add a dummy assert_id (not needed here)
- only test assert_id for other if not AEADKeyBase instance
- remove test_getting_wrong_chunk. assert_id is called elsewhere
and is not needed any more anyway with the new AEAD crypto.
- only give manifest (includes key, repo, repo_objs)
- only return manifest from Manifest.load (includes key, repo, repo_objs)