ToDo: Breaking change to update to Preact 7

[developit]

Preact 7 actually makes MDL vastly easier to work with, because it no longer requires crazy DOM crawling code to evade the recycler. preact-mdl needs to release a new major version that removes all the crawling, and only allows Preact 7+ as a peer dependency.

[impronunciable]

It's Britney, bitch

[developit]

Oops, I did it again!