Pick a starting count in a wider range

Counter should be a random number between 1 and 65536, rather than between 1 and 18.
Merge pull request #5 from tsukasa-au/patch-1

Pick a starting count in a wider range
Fix module docstring for inventory example.
Ensure that the response key is set even for errors.
Make Location objects copy/pasteable.

After this change, you can copy/paste a Location object when working
directly in the interpreter.