2.2.4
=====

add support to Constant to retrieve members by value

    --> class K(Constant):
    ...     one = 1
    ...     two = 2

    --> K.one
    <K.one: 1>

    --> K(1)
    <K.one: 1>

add pickle/deepcopy support to Constant

add support for Constant to use other Constant values
  (resulting members /are not/ the same)

    --> class C(Constant)
    ...     one = K.one
    ...     three = 3

    --> C.one == K.one
    True

    --> C.one is K.one
    False

AutoNumber and auto() now work together

Enum members are now added to the class as enum_property, which supports
unshadowing of parent class attributes when called on an Enum member:

    --> class StrEnum(str, Enum):
    ...     lower = 'lower'
    ...     upper = 'upper'
    ...     mixed = 'mixed'
    
    --> StrEnum.lower
    <StrEnum.lower: 'lower'>

    --> StrEnum.lower.upper()
    'LOWER'

    --> StrEnum.upper
    <StrEnum.upper: 'upper'>

    --> StrEnum.upper.upper()
    'UPPER'


2.2.3
=====

use members' type's methods __str__, __repr__, __format__, and
__reduce_ex__ if directly assigned in Enum class body; i.e.:

    --> class Color(str, Enum):
    ...     red = 'red'
    ...     green = 'green'
    ...     blue = 'blue'
    ...     __str__ = str.__str__

    --> print(repr(Color.green))
    <Color.green: 'green'>

    --> print(Color.green)
    green


2.2.2
=====

replace _RouteClassAttributeToGetattr with enum_property (it is still
available as an alias)

support constant() and auto() being used together:

    --> class Fruit(Flag):
    ...    _order_ = 'apple banana lemon orange'
    ...    apple = auto()
    ...    banana = auto()
    ...    lemon = auto()
    ...    orange = auto()
    ...    CitrusTypes = constant(lemon | orange)

    --> list(Fruit)
    [Fruit.apple, Fruit.banana, Fruit.lemon, Fruit.orange]

    --> list(Fruit.CitrusTypes)
    [Fruit.orange, Fruit.lemon]

    --> Fruit.orange in Fruit.CitrusTypes
    True


2.2.1
=====

allow Enums to be called without a value

    class Color(Enum):
        black = 0
        red = 1
        green = 2
        blue = 3
        #
        @classmethod
        def _missing_value_(cls, value):
            if value is no_arg:
                return cls.black

    >>> Color()
    <Color.black: 0>

allow Enum name use while constructing Enum (Python 3.4+ only)

    --> class Color(Enum):
    ...     _order_ = 'BLACK WHITE'
    ...     BLACK = Color('black', '#000')
    ...     WHITE = Color('white', '#fff')
    ...     #
    ...     def __init__(self, label, hex):
    ...         self.label = label
    ...         self.hex = hex


2.2.0
=====

BREAKING CHANGE
---------------
In Python 3+ classes defined inside an Enum no longer become members by
default; in Python 2 they still become members, but see below.

For cross-compatibility and full control two decorators are provided:

- @member  --> forces item to become a member
- @nonmember  --> excludes item from becoming a member

So to have an Enum that behaves the same in Python 2 and 3, use the
decorators (and other compatibility shims):

    class Color(Enum):

        _order_ = 'red green blue'

        red = 1
        green = 2
        blue = 3

        @nonmember
        class Shades(Enum):

            _order_ = 'light medium dark'

            light = 1
            medium = 2
            dark = 3


2.1.4
=====

EnumMeta:
- change __member_new__ to __new_member__ (as the stdlib enum does)
- assign member name to enum() instances (an Enum helper for defining members)
- handle empty iterables when using functional API
- make auto() work with previous enum members
- keep searching mixins until base class is found

Enum:
- fix bug in Flag checks (ensure it is a Flag before checking the name)
- add multiple mixin support
- do not allow blank names (functional API)
- raise TypeError if _missing_* returns wrong type
- fix __format__ to honor custom __str__

extend_enum:
- support stdlib Enums
- use _generate_next_value_ if value not provided

general:
- standardize exception formatting
- use getfullargspec() in Python 3 (avoids deprecation warnings)


2.1.2
=====

when order is callable, save it for subclass use


2.1.1
=====

correctly raise TypeError for non-Enum containment checks
support combining names with | for Flag key access
support _order_ being a callable


2.1.0
=====

support Flags being combined with other data types:
- add _create_pseudo_member_values_ 
- add default __new__ and temporary _init_ 


2.0.10
======

ensure _ignore_ is set when _settings_ specified in body which includes
AutoValue

make Flag members iterable


2.0.9
=====

fix missing comma in __all__
fix extend_enum with custom __new__ methods
fix MultiValue with AutoNumber without _init_


2.0.8
=====

extend_enum now handles aliases and multivalues correctly


2.0.7
=====

support mixin types with extend_enum
init and AutoNumber can now work together
add test for new Enum using EnumMeta
add tests for variations of multivalue and init
prevent deletion of NamedConstant.constant


2.0.6
=====

constants cannot be deleted (they already couldn't be changed)
constants can be used to define other constants


2.0.5
=====

_init_ and MultiValue can now work together


2.0.4
=====

_init_ and AutoValue (and _generate_next_value_) can now work together to
supply missing values even when some of the required values per member are
absent


2.0.3
=====

add _missing_value_ and _missing_name_ methods, deprecate _missing_
make enum instances comparable


2.0.2
=====

both EnumMeta.__getattr__ and Enum.__new__ fall back to _missing_


2.0.1
=====

auto() now works with other data types
AutoNumber supports legacy Enums (fixed regression)


2.0.0
=====

Flag and IntFlag added.


1.4.7
=====

fix %-interpolation bug
defined SqlLiteEnum only if sqlite exists
support pyflakes


1.4.6
=====

version numbering error


1.4.5
=====

revert AutoNumberEnum to custom __new__ instead of AutoNumber
use _ignore_ to shield against AutoNumber magic
inherit start and init settings from base Enums


1.4.4
=====

enabled export as a decorator
enabled _order_ to replace __order__
enabled python2 support for settings, init, and start


1.4.3
=====

support _ignore_ for dynamically creating class bodies


1.4.2
=====

MultiValue, NoAlias, Unique, and init now work with Python 2


1.4.1
=====

Py3: added Enum creation flags: Auto, MultiValue, NoAlias, Unique

fixed extend_enum to honor Enum flags


1.4.0
=====

When possible aenum inherits from Python's own enum.

Breaking change: enum members now default to evaluating as True to maintain
compatibility with the stdlib.

Add your own __bool__ (__nonzero__ in Python 2) if need this behavior:

    def __bool__(self):
        return bool(self.value)
    __nonzero__ = __bool__