TextArea: use TextEdit::append()

Change-Id: I30f23198cd82f26f92d3b7cae47e2ac64d1fad9b
Reviewed-by: Caroline Chao <caroline.chao@digia.com>
TextArea: switch to Qt.PointingHandCursor when hovering links

Change-Id: I7c306093c1afc9f5dfe942cd29da427c6a57d869
Reviewed-by: Caroline Chao <caroline.chao@digia.com>