- delete outdated impls on PUTing new one

- (!) Editors' workflows:
  - (?) log all (including editros) posters of particular document to minimize conflicts about why somthing was changed
    or better, detailed log for every editor's change

- Remove temporal security hole with speciying guid in POST,
  it was added as a fast hack to support offline creation (with later pushing to a node)
- GC implementations cache
- get all localized strings from activity.info while populating local contexts
- activities migth need MIME registering while checking-in
- changed pulls should take into account accept_length
- i18n activity.info's strings
- handle DELETE while calculating per-object node stats
- unstall activities on checking out and on initial syncing
- increase granularity for sync.chunked_encode()
- slave._Pooler might leak events if pullers are not in time to call wait()
- revert per-document "downloads" property as "launches", a part of unpersonizalied user_stats
- more useful offline workflow
  - keep offline Contexts synchronized with online source
  - (?) not only new content in offline mode
- handle proxy prpos for prop= requests
- reuse "layer" for home volume instead of "clone" and "favorite"
- local preferences regarding feeds
