Reduced alphabet size when initializing a Hashid object and the hashids argument is not None

[sgex]

This commit a8e8366 seems to be incorrectly copying the alphabet at line 19 (self._alphabet = hashids._alphabet).

In Hashids the alphabet does not include separators so the alphabet argument passed into the constructor of Hashids is different from self._alphabet.

A common input alphabet is 0123456789abcdef. After separators are removed, hashids._alphabet will have fewer than the minimum of 16 characters, which is possibly the cause for #44

The old code didn't have this problem because it was not reading hashids._alphabet

[nshafer]

Thanks for the detailed report. I still can't reproduce #44, but this definitely caused issues with pickling and unpickling. I have fixed it in 3.3.0.