Renamed __pretty__ to _repr_pretty_ and changed updated pretty.py...
Renamed __pretty__ to _repr_pretty_ and changed updated pretty.py
* Throughout the codebase, __pretty__ has been changed to
_repr_pretty_ to match general convention for special method
names.
* The logic in pretty.py now matches that in formatters.py in that
formatters that are callables are tried first and then special
methods are used.