[TASK] Deprecate the removal of invisible nodes

[oliverklee]

Relates to #252

[oliverklee]

@jjriv @zoliszabo I'd like to have feedback from both of your before this gets merged.

Note: I'm thinking about creating a new class HtmlMinifier that then will provide methods for removing invisible nodes and removing class attributes (both with separate methods).

[jjriv]

I think Emogrifier should preserve the original contents of the email while also making it email friendly. This includes keeping HTML elements with display equal to none.

I do like the idea of adding a minifier class. This would keep the purposes for each class seperate. And minification is a nice feature. But also see my comments on the original issue because I don't want it to become something that is a pain to support. The benefits need to outweigh the efforts required to support it.

[oliverklee]

Now that we agree on the roadmap, a review and merge would be nice. 😄