Combining CleverDict functionality with other classes

[PFython]

It would be great if CleverDict behaviour could be easily 'grafted on' to existing classes using inheritance, without causing recursion or requiring a rewrite/overwrite of the original class.

For example if it were as easy as:

```
>>> class MyDatetime(datetime.datetime, CleverDict):
...     pass

>>> mdt = MyDatetime.now()
>>> mdt.hour
4
>>> mdt['hour']
4
```

[PFython]

Labelled as "wontfix" after Version 1.8.0 simply because the main authors don't currently have the time for non essential enhancements. If there's a huge uptake in people using CleverDict and asking for this feature that may change, or if you're reading this why not Fork, develop a solution, and contribute a Pull Request yourself?