* Fix enum members getting shadowed by parent attributes
* Move Enum._convert to EnumMeta._convert_
* Deprecate _convert

add private method to enum to support replacing global constants with Enum members:
- search for candidate constants via supplied filter
- create new enum class and members
- insert enum class and replace constants with members via supplied module name
- replace __reduce_ex__ with function that returns member name, so previous Python versions can unpickle
modify IntEnum classes to use new method