Handle non-printing characters in property names

It is currently possible to create duplicate-looking property names due to the inclusion of non-printing Unicode characters. Some of these characters are commonly generated by certain word processing or spreadsheet software. It seems like an extreme edge-case that an end-user would deliberately included one in a property name. I can see arguments for either stripping non-printing/control unicode characters by default or rejecting input property names containing them and would personally be happy with either provided there was appropriate feedback either via API and UI.