Add render / match function to the tree

[thewebartisan7]

Add render and match function to the tree using posthtml() function, something like posthtml-modules is doing here https://github.com/posthtml/posthtml-modules/blob/master/index.js#L125 or just set match and render function on tree before next process.

Originally posted by @thewebartisan7 in #21 (comment)