Instead of simply returning the content text view from hitTest(_:with:),
we need to call the super method so that the system still performs its
own checks.
UITextView uses TextKit internally, unlike UILabel, so no additional
code is needed to keep the TextKit and view representations of the text
in sync since they are one and the same. This means that detecting which
character was tapped in a content text view is much more accurate, which
means link handling is substantially imrpoved.
Fixes#20
Shadowfacts