Add containerClassList to Settings

[jouderianjr]

Hi everyone, I've been using this package and works great.

My idea is to add one more field to Settings type, containerClassList, in order to get a more flexible view, I was doing some style in my project and I'm having some problems with the container default style.

If everyone thinks it's a good improvement I can open a PR for this.

Thanks 💃

[bbqbaron]

Nice idea! Sometimes I say to myself, "Well, if we add enough settings the user may as well just render their own view!", but since this isn't complicated I don't think it's any more of a problem. PR welcome!

(It will cause a major version, of course. Sometimes I wonder if we should use an opaque type like Model with a bunch of getters/setters just to let us implement optional fields like Reason has, but that seems like an antipattern just to get around a shortcoming of the type system. </idle_musings>)

EDIT: Markdown should have semantic fencing for passages that are just 🤔 .

[bbqbaron]

Merged! #80 and #81 have recent activity on them, so I was thinking I might try to bundle any resulting work together as a single release (since #80 is likely to cause a major version as well).