Support derived Animate classes in order to use the same axes.

[tahsinkose]

Hello there,

I've been using the MATLAB version of these nice toolboxes and just recently finally had a use-case to migrate to Python. I needed to visualize multiple frames in a single animation view. In order to do that, I have to derive from base.animate.Animate and adjust some of the internal data structures. In order to use the same ax as base.animate.Animate does, however, I had to clone this repo and make this change so that all derived classes receive the exact same treatment with the base class.

[tahsinkose]

@jhavl this is a rather simple yet capable improvement that provides trivial extensibility of Animate classes. Could you please give it a quick look and merge? 🙏🏼

Cc. @petercorke

[petercorke]

Looks great! I'll have a look at the change on the weekend. There's more I'd like to do with animations but this seems like a win. Thx for your interest

[tahsinkose]

@petercorke friendly ping 🙂