Blitting support

[t-makaro]

In past tests, blitting has caused issues with the play/pause button. I'll need to experiment with it a bit, and maybe make changes to the Block._update methods.

An option in the Animation class to enable blitting would be ideal.

Worst case scenario, blitting isn't possible with the pause button, and I'll issue a warning if both are used.

[t-makaro]

I'm getting some very strange issues, but neither the slider or pause button work properly with blitting. Blitting works perfectly if neither of the controls are used. I also don't think that %matplotlib notebook uses blitting at all since I can't determine any difference between using blitting and not in a notebook.

I think I may wait until matplotlib 3.0 to continue further experiments with this since they are refactoring their blitting system.

[TomNicholas]

Did you manage to get any further with this? Matplotlib is on v3.0.2 now, did they refactor their blitting system?

If there's really no blitting at all in %matplotlib notebook if would be useful to know if that's because of a bug or some active decision by someone.

[t-makaro]

I haven't looked into this yet.

Dev note: Exploring this involved changing the call to FuncAnimation in the Animation call to use blit=True. I previously found that the pause button in particular caused problems.