This is to reduce duplication in the plugins.  Instead of repeating the merge and events code, they can just borrow the existing code from window.PouchDB.merge and window.PouchDB.events.  See `plugins/merge-browser.js` and `plugins/merge-events.js`.

Along those same lines, there has got to be a way to reduce the amount of code in the plugins - mostly they are full of Buffer code, and I'm not sure how much is actually needed for PouchDB.  But we can address that in later releases.