Input/output calls

...development access. Deprecating xhtml() and _html()
Perhaps this should wrap around `rawHtml` because that more closely resembles what it used to do, here, in this line.

The trouble could be, if implementations upgrade WYMeditor and don't replace their `_html` calls with the parsing `html` call.

@winhamwr what do you think? What should this wrap around? Perhaps it should be completely removed to force users to get it right?