- now mark methods with strict deprecation, to make it easier to find
  their use but without adding extra compilation noise for others

ENH: minor update for Enum methods and iterator

- add warnOnly (failsafe) option for readEntry and getOrDefault

- add good() method to Enum iterator (simliar to HashTable)

- replace unused/fragile Enum find() methods with iterator return
  that can be used more generally