we seem to have MANY_TO_ONE and MANY_TO_MANY constants that happen to be used as ReferenceOne / Many fields, which seems a bit funny. but it gets a lot worse in places like https://github.com/doctrine/phpcr-odm/blob/master/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php#L1036

i wonder if we can still do a bunch of constants for all that. not sure why they are numeric constants and not strings, but constants they should become. @lsmith77 wdyt?