wiki: Validate wiki markdown with the wiki md processor.
filters: Allow a links to have rel as soup replaces nofollow with them.
filters: Allow id as an attribute
Wiki: Replace TOC with a python generated one

- Replaces terrible anchor links with header content based ones
- Fixes quirks with oddly ordered headers
- Fixes html in headers appearing as text in TOC
Wiki: Fix unicode encoding issue
Revert "Temporarily use "[deleted]" in JSON for deleted usernames."
Use an absolute URL for self-posts for the embeddable widget
Provide developer-friendly attributes in the modaction json.