Thoughts on how to improve performance

The biggest performance issue that currently every tracked figure gets a full redraw every frame: https://github.com/ianhi/mpl-playback/blob/06a7faf567e487b49d32468767fd90fb5f659ec9/mpl_playback/playback.py#L245-L248

This happens even if the event has already triggered a draw if for example a slider was moved.

Potential solutions:

1. Only redraw figures if they have stale=True
2. monkeypatch figure's draw events to prevent the earlier draws and only do our final draw
3. In combination with 1 blit the fake cursors