Drag context child into another context

[raineorshine]

Steps to Reproduce

- Film
  - To Watch
    - Movies
      - Days of Being Wild
        - 1991
      - Fallen Angels
        - 1995
  - Watched
    - Movies
      - In the Mood for Love
        - 2000

1. Activate context view on Film/To Watch/Movies.
2. Set the cursor on Film/To Watch/Movies/To Watch.
3. Drag Fallen Angels into Watched.

Current Behavior

Fallen Angels gets duplicated in Watched and there is a warning.

Invalid parentId: sourceThought.parentId does not match parentOf(oldPath).

Expected Behavior

Fallen Angels should be moved to the end of Watched/Movies:

- Film
  - To Watch
    - Movies
      - Days of Being Wild
        - 1991
  - Watched
    - Movies
      - In the Mood for Love
        - 2000
      - Fallen Angels
        - 1995

Testing

Add a moveThought reducer test.