More dict functions should warn

[NOhs]

The following functions do not work as expected:

pop(key)

should return the correct value and also warn if a deprecated key is used.

clear()

should remove the deprecated lookup dict.

copy()

should return a dict that still warns

del my_dict[deprecated_key]

should warn before removing correctly

key in dict

should return the correct value (true in case of a deprecated key) and warn

items(), keys(), values()

are also not supported as of now, they do not contain the old keys

__iter__

should also be adapted, currently it does not yield a list with the old key and also does not warn.

[NOhs]

Fixed with #10