Restore 3.5 compatibility

[phixtyseven]

Proposing a possible patch in response to #45.

Changes:

• A new function in Utils.py called random_choices, essentially a watered-down version of random.choices
• Replacement of all references to random.choices with random_choices

I would appreciate any feedback. I don't know whether compatibility with older versions of Python 3 is even a priority of the project. I've tested the changes to work with 3.5 without issues. Also, I wasn't sure whether Utils.py is intended to host this kind of thing, that's just where I happened to stick it.

This is my first pull request, so go easy on me. :p

[AmazingAmpharos]

This is not a particular priority but this has mixed a few people up and should in theory be a strict improvement. I'll merge this in.