Fix nested tags inside of script tags.

Added some extra logic inside of the script tag specific piece of the parser to allow nested tags inside of script tags.  It used to infinite loop.

#115
- in your first new test (`<script></p></script>`) and if the earlier comments are correct, current should always be at the '/' in `</p>` at this line.  `SkipToAndParseCode()` should happily move ahead to the `'<'` at the start of `</script>`.  why exactly doesn't it advance?
- put another way, why does it take two `AcceptAndMoveNext()` calls to avoid looping endlessly? is the real bug that the `NextIs(HtmlSymbolType.ForwardSlash)` block is putting one too many tokens back?

- nit: http://www.unnecessaryquotes.com/