Partial special rendering syntax #503

Hey, I've been using and loving maud.

Partials work flawlessly by expression interpolation, but it breaks a lot of maud's HTML-like structure when you start to nest a lot of partials with children, because you end up repeating "html!" a lot.

My question is, would it be of interesting of maud having a partial like especial syntax alongside de expr interpolation that specifically allowed for streamlined children annotation? I think it fits the library, because it's basically the same as "if" and "for" syntaxes, but for partials.

An example of the syntax can be found in a library I authored, in which I copied maud's syntax (mostly) and just added this bit. Reference.

If it is something that interests this library, I could try to provide a PR for it.