Added ability to de-render after saving in Evernote, Google Sites, Blogger, and Gmail drafts. Not fully tested elsewhere yet. This will hopefully resolve #85, #86, #65.
Finding MDH wrappers now work properly.\nFILTER_REJECT was causing all child elements to be skipped as well, which is undesirable.
Dumbed-down some code to work with Postbox. Except it still doesn't work with Postbox.
Altered H1 and H2 styles to match new GitHub styles.
Thunderbird throws away the original-MD div if it's empty, so now there's a zero-width space in it.
Fixed bug with Postbox not rendering. (Still doesn't unrender, though.)
Fixed derendering in Postbox. Probably made Mozilla logging more reliable.
Use base64 instead of URL encoding for raw MD. Strip whitespace to help deal with Thunderbird's habit of adding newlines.