undefined formatting of <note> text leads to roundtripping issues

[anthrotype]

https://unifiedfontobject.org/versions/ufo3/glyphs/glif/#note

This element is a place for the user to define arbitrary text about the glyph. There is no standardized structure for the note apart from that it being the content of the note element.

This "no standardized structure" leads different implementations to do different things with the note, making it hard/impossible to maintain its text unchanged when passing through alternative UFO parser/writers.

see fonttools/fonttools#2745

As for the fontTools.ufoLib (reference) implementation, it currently does the following:

• upon serializing, a newline is inserted at the beginning and at the end of the text content (presumably so that the element tags are on a separate line);
• then upon deserializing, newlines are normalized to unix line endings \n and all leading/trailing whitespace is stripped from each line, empty lines are stripped too.

I think the spec should just mandate the above for the sake of interoperability. It's probably too late to change fontTools.ufoLib semantics around <note>.

[benkiel]

Agree that we should just note that. Will make a PR. Please ping me if I've not by weeks end (many things going on)