Fullscreen comment editor & much improved HTML sanitization.

* Implemented a 2 column full page comment editor  for working on big posts/comments.
* Image viewer now uses a custom SnuOwnd context for HTML sanitization (Fixes raw HTML showing in many cases).
* Updated SnuOwnd for wikis.
* Fixed some cases in `saveComments` where a WebKit bug could cause an entire `window` object to leak when a page refreshes. (This bug *might* have actually been fixed in Chrome Canary as recently as today)
* Fixed a bug that prevented text expandos from closing.