TODO

# TODO
- [x] Add an `.editorconfig` and `.pylintrc` to define code layout
- [x] Add support for highlights and bookmarks into a metadata field
- [x] Make the warning about synced metadata more informative
- [x] ~~Add support for `MTP_DEVICE` devices~~
- [x] ~~Add support for multiple storages (i.e. SD cards) for `MTP_DEVICES`~~
- [x] Add support for `KINDLE2` devices
- [ ] Build in a fail-safe when a sync would delete existing metadata (i.e. only add)
  ```python
  d = difflib.Differ()
  diffs = list(d.compare(
    metadata.get(key).splitlines(),
    new_value.splitlines()
  ))
  ```
- [ ] Fix all pylint errors and warnings
- [ ] Add `last_page` for PDFs instead of `last_xpointer`
- [ ] Add support for highlights and bookmarks into the `annotations` table in calibre's `metadata.db`
- [ ] USBMS devices have `calibre.devices.usbms.cli.CLI.list()`. Use that to find sidecars (and their mtime?), instead of trying paths that might not exist? (Note that `calibre.devices.smart_device_app.driver.SMART_DEVICE_APP` does not have a `list` function.)
- [ ] Sync from calibre to KOReader?