make matplotlib optional

[TheTripleV]

closes #100

[Daltz333]

Will this break any existing users (aka is it opt-out instead of opt-in)?

[sciencewhiz]

Well the issue from #100 was asking for it to be opt-in, since it was added recently, right?

[TheTripleV]

If matplotlib is installed, it's opt out. If matplotlib isn't installed, it doesn't run. So it should keep existing behavior.

[Daltz333]

So this should only break CI environments for users. That still is pretty bad, but I'm not sure there is a better solution.

[TheTripleV]

No it shouldn't break ci for anyone. If matplotlib isn't installed it just turns off image generation

[Daltz333]

I wish there was a behavior where we automatically instead matplotlib and the user can explicitly choose not to instead it, instead of the opposite.

[TheTripleV]

I don't think that's possible