Update to v3+ style extension

[tdreyno]

We're dropping support for the old module-based extension format in v4. Noticed you're still on the old version. Would love if you could update.

Here are the docs on the newer format (which works for the entire v3 series and up): http://middlemanapp.com/advanced/custom/

[porada]

Finally updated. Thanks for reporting this.

Are the v3 apps compatible with Middleman v4? I’d like to test the fixture apps against it.

[tdreyno]

Yes, the "v3" format was introduced in Middleman 3, but we only deprecated the old format. In v4, we're dropping support for the old format and keeping "v3" only. Probably needs a better name :)

[porada]

Let me rephrase the question: are v3 apps (and not only extensions) compatible with Middleman v4 by default? 😉

[tdreyno]

@porada For the most part, they are compatible. We've remove a bunch of feature many users didn't use and moved them into optional extensions instead.

If you've got an older app that isn't working out of the box, I'd love to see what the messages are. We may have overlooked something.