Feature request: Require UTF-8 Everywhere (aka; Allow me to be hostile to myself)

I was just reading this ( http://beets.io/blog/paths.html ) and almost jumped out of my chair when I read

> One day, I believe we will live in a world where everything is UTF-8 all the time. **We could hasten that glorious day...**

As someone who works closely with files, I can't even count how many hours I've spent moving closer to that world.

I welcome the ability to be 'hostile' to myself as a user if it means rejecting all other encodings and enforcing UTF-8.

The issue names no files, tests, or entry points. Start by clarifying which file and metadata operations must reject non-UTF-8 input and how enforcement should be configured. Define completion as documented behavior and tests covering the agreed encoding boundaries.

Written by the indexing model from the issue text.