Remove compatibility symbols (Proposal 19)

[MDLC01]

Description

This PR implements Proposal 19 (iteration 1 iteration 2) from the Symbol Proposals document. It removes compatibility codepoints. For some context, see the Unit Symbols paragraphs of section 22.2.1 of the Unicode 16.0.0 Core Specification, as well as the description of Proposal 19 in the aforementioned Symbol Proposals document (copied below for simplicity).

Breaking changes (cc. @laurmaedje)

angle.l.double and angle.r.double change codepoints. degree.c, degree.f, ohm, ohm.inv, angstrom, and kelvin become invalid.

[MDLC01]

Regarding U+2127 ℧, which this renames to mho, I'm thinking it could make sense to add it as Omega.inv in addition (or in place of) mho.

[laurmaedje]

I'm okay with removing the compatibility symbols.

[mkorje]

I agree we should add Omega.inv, and I'd argue in place of mho since I imagine a user might expect ohm to also work then. But as mho is a Unicode informative alias and I don't know anything about its use, I'm not quite sure if omitting mho would be good or bad.

[dccsillag]

+1 for `Omega.inv`.

…

On Dec 12 2024, at 11:21 am, Max ***@***.***> wrote: I agree we should add Omega.inv, and I'd argue in place of mho since I imagine a user might expect ohm to also work then. But as mho is a Unicode informative alias and I don't know anything about its use, I'm not quite sure if omitting mho would be good or bad. — Reply to this email directly, view it on GitHub (#14 (comment)), or unsubscribe (https://github.com/notifications/unsubscribe-auth/ADXE2C2ZRCNAT3LEEMRUSOD2FGLVTAVCNFSM6AAAAABSXGAGMSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKMZZGA4TCNRSGQ). You are receiving this because you are subscribed to this thread.

[MDLC01]

I replaced mho with Omega.inv, as "mho" seems to mostly be an outdated unit.¹ Of course, we can always add mho later if necessary.

Footnotes

1. https://en.wikipedia.org/wiki/Siemens_(unit)#Mho ↩

[Enivex]

It's so cute though!