git-subtree-dir: omemo/lib/python-omemo
git-subtree-split: b396ef99d7665e82d9d5dafe83473f2e9d0cba66

We did not do a conversion to unicode as needed

This will allow to easier split up in to own package. See also
omemo/gajim#22

If you are working on `gajim-omemo` you can just use `./launch.sh -l
plugin_system.omemo=INFO` to get only the important bits.

- Remove UI.available logic. UI object is now only created if needed
- Remove UI.last_plain_msg logic. If a plain message is received we just print a
warning as status msg
- Simplified OmemoState.device_ids_for
- Should fix #16 & #18

- All the logic is in the Checkbox
- Use unicode LOCK & OPEN_LOCK chars