#95 Docs for Enum::Next() do not match implementation

[Jeff Downs]

For those Enum interfaces that are generated via the
dodo-supplied Enum macro, the documentation produced
for the Next() method does not match the actual
behavior in the implementation. Most (all?) of the
Enum's share a common implementation.

Specifically at issue is the ambiguously documented
behavior when you are near the end of the enumeration.
The success conditions list that there must be items
left in the enumeration. However, there is no return
code for this.