Issue: Implement XF2.3 Embed content anywhere

Like other local links in XF 2.3, links to wiki content in the forum will automatically convert to the new EMBED BB-Code, which will embed a preview of matching content. The following types will be embedded, based on the URL:

• A wiki page will show rendered preview of the page text.
• A wiki feed will show the feed description.
• A wiki special page will show a small subset of the special page results.
• A wiki synonym will show the rendered preview of the synonym target.
• A wiki synonym's view action will show the unforwarded synonym view.
• A wiki custom tab (custom field tab renderer) that shows only an embedded wiki page or wiki attachment, will show the rendered preview of the tab's embedded content.
• A wiki comment will show a rendered preview of the comment text.
• A wiki discussion will show the discussion description.
• A wiki topic (not yet created as a discussion) will show the topic description.
• A wiki feed entry will show a rendered preview of the entry content.
• A wiki edit from its history will show the change list from that edit.
• A wiki file update from an attachment's history will show the change list from that file change.

I think we covered everything that natively resolves to specific content. If not, please raise it as a bug in the next release.

We are still working on making sure that the sharing options are available for all this content, so that the embed code for external sites is readily available.

Required embed codes have been added to the various content type views. Marked as Implemented in the next release.

As this resolves the last change needed for XenForo 2.3 support, we should be able to package the new release over the next day or two.