Preserve quoted strings and do not output empty class attributes

1. Do not output empty class attributes if styles are not specified
Example: a.{beep}
before: <a class>beep</a>
after: <a>beep</a>

2. Do not split between quotes
Example: a[href="one.more.link.to.follow"].bling{beep}
before: <a class href="one ]">more</a> ....
after: <a href="one.more.link.to.follow">beep</a>