Fix Links Not Taking adjustsFontSizeToFitWidth into Account

It looks like at some point #37 resurfaced. The set of `attributedText` at the end of `drawTextInRect:` resets the `framesetter` and `renderedAttributedText` properties, the former of which is used by `characterIndexAtPoint:` to determine if a tapped point is inside a link.

Using the ivar directly to bypass the setter is maybe an ugly solution, but it's the simplest thing I could see to fix this issue.