Reading GIF information and getting playback callbacks

In a similar way to #192, this would be a feature request to get information from the loaded gif in terms of playback time, and being able to get callbacks on each frame to update the playback position. Think of implementing a video like UI on top of gif playback. Did look through the API and didn't find how this would be possible. Desired features:
- Get total playback of the gif in milliseconds and/or frames.
- Get current playback position in milliseconds and/or frames.
- Seek to a specific playback frame.
- Be updated on each frame through a callback.