Editorial: revamp the way we deal with code points and bytes

[annevk]

This is WIP, mainly since I'm a little unsure we want to go this far, but I also kinda like it.

@andreubotella @ricea @domenic @aphillips thoughts?

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[domenic]

Seems reasonable to me.

[ricea]

Am I understanding correctly that the purpose is disambiguate code-point and byte conversions?

If so, my concern is that the extra rigor creates extra opportunities for errors, and may not be pulling its weight.

However, if you prefer it, that's good enough for me.