HTML value textarea input through `.html()`

We should probably be parsing it, otherwise, we'll hide issues where the HTML will be changed later on. I'm worried about the performance impact with this change, though. Parsing can be expensive and re-parsing on each keystroke will likely result in negative UX, especially in IE7. This has the potential to make direct HTML editing unusable.

Suggestions to mitigate this:

* Only modify the HTML on the word-boundary characters (space, return, backspace, delete, `>`)
* Some kind of settimeout juggling so that we only re-parse a max of e.g. once every 500ms

In light of that, I'm not sure if this is something we want to focus on right now. Your call.