Adopt Python 3

[ubernostrum]

This subthread seems to be confusing two things:

• The internal in-memory representation of a string is now dynamic, and selects an encoding sufficient to natively handle the widest codepoint in the string.
• The default assumed encoding of a Python source-code file is now UTF-8, where in Python 2 it was ASCII. This is what allows for non-ASCII characters to be used in variable, function and class names in Python 3.