Move append_output animation height lock release into timeout.
Use .load() to resize
Try removing the callbacks
A couple of fixes,

- Fix missing `type` from png/jpeg check
- Don't resize on weird chr(13) stand alone stream msgs
Make sure to not call old load events
Cleanup
Don't send \r characters in zmqshell clear_ourput
Make qtconsole aware of clear_output.
Make `ipython console` aware of clear_output changes.
Address @takluyver's comments.
Merge pull request #5459 from jdfreder/ff_animhop

Fix interact animation page jump FF