Libertinus: Some operators have wrong sizing and alignment

[philosaurus]

U+221F, U+2227–U+222A and U+228C–U+228E are placed on the baseline rather than being centered on the math axis. They also seem to be a bit small. The U+2229 and U+222A should probably be more similar in appearance to a rotated U+2282.

The + and × are only included in the image for reference.

[khaledhosny]

It is always good idea to check what other math fonts are doing here and what happens when the math font is used by a math layout engine (*TeX math mode, for example).

[philosaurus]

It's the same in XeTeX and Word. All other maths fonts I have are correctly aligned, so are other symbols in Libertinus.

[alerque]

Note to self or anybody else that works on this: while checking math symbol alignment also review whether +lnum vs. +onum features do/should affect what center line is used. See example this comment on Elstob.

[alerque]

Clearly @thlinard is somebody to ping to review alignment when a PR is ready for this :wink:!

[ivo-s]

Hey @philosaurus, see #454 for dicussion about resolving this issue. I am also pinging @thlinard concerning the alignment discussion in the same place.