Added Core Text kern attribute

Set it to 0.0 to avoid kerning so that it renders the same as UILabel
and UITextView.

Signed-off-by: Yi Qiang <yqiang@gmail.com>
UIResponder replaced by a UITapGestureRecognizer

This way it's easiar to handle links with other gesture recognizers
using for instance requireGestureRecognizerToFail:

Signed-off-by: Yi Qiang <yqiang@gmail.com>
Link state remaining active on tap and hold a link and then scroll fixed

Signed-off-by: Yi Qiang <yqiang@gmail.com>