Add this to types repo

[winksaville]

Hello, I see in this issue that you suggested adding this directly to mithril.js, too bad that didn't happen :(

But I see you suggested adding it to DT, but I'd like to suggest instead of that, or maybe in addition to that, you add it to types so typings can be used for managing.

[spacejack]

Hi - this is getting merged into the mithril.js repo actually. Should be included in the next release.

[winksaville]

Nice!!!!