Remove flavor 3 checking as it no longer exists

We can now just check "m_flavor == 2" directly instead of checking part
of the bits to see if it is 2 or 3.
Rename rising/falling to leading/trailing edge
Add ok() method to HcalUHTRData::const_iterator

This method works for flavor 2 and 4; all other flavors do not define an
OK bool and so it returns 'false'.