Limit JSON in the DOM

We have been keeping json for items and pages in the dom. This was once a primary storage for editing. Now it is less used, sometimes out of date, and an impediment to healthy models.

Page

All of these references should be replaced by pageObject, possibly retrieved from the lineup by key. This is safe even though we still have some lineup ordering issues with mass-reloads.

✔ Used in legacy for JSON footer link.

✔ Used in legacy for rev timestamp double-click.

✔ Used in legacy for action click to get rev slug from title.

✔ Used in legacy to fork/push page from local storage.

✔ Used in pageHandler to fork/push page into local storage.

Set in refresh from pageObject.

✔ Used in state to set tab title, 2x. Delegate to lineup.

✔ Used in test/refresh to inspect constructed page.

Used in plugin/reduce to find pageFold of links, 2x.

This last reference is hard to resolve. One approach would be to expose the wiki-client lineup to plugins through the wiki global. This leaves a coordinated release problem between the wiki-client and the plugin-reduce repo.