Allow for enum docstrings

A friend showed me a different enum package with support for enum item docstrings. The syntax was something like:

from flufl.enum import Enum

class Color(Enum):
    red = (1, 'The color red')
    blue = (2, 'The color blue')
    green = (3, 'The color green')

i.e. assignment of a tuple where the first element is the value and the second is the docstring.

While this is a neat idea, I think the syntax conflicts with existing semantics where tuple values are perfectly valid. Perhaps something like the following could work though:

from flufl.enum import Enum, Value

class Color(Enum):
    red = Value(1, 'The color red')
    blue = Value(2, 'The color blue')
    green = Value(3, 'The color green')