Character sets from HP 4260 Series terminals

[PhMajerus]

The Hewlett-Packard 2460 Series terminals from the 1970's offered several characters ROMs with some characters not commonly found on other terminals.
Much more details about those terminals can be found at https://www.curiousmarc.com/computing/hp-264x-terminals

The Roman uppercase and lowercase are the standard 7-bit ASCII, but require control pictures and a checkerboard delete symbol:

Both are included in my #144 pull request.

The line drawing ROM contains some very unusual lines, which have been recently added to Unicode 16.0 as part of the Symbols for Legacy Computing Supplement. They are also included in my #144 pull request.

The Large Type Pieces ROM is a amazing exclusive set of characters, also included in #144.

The Math symbols ROM contains mostly Greek and a few extras, and these are still not complete.

Namely, we need ≃ (U+2243) and ☨ (U+2628) to be added to support everything.

Here are the character ROMs as text:

 Roman Uppercase   Roman Lowercase
  !"#$%&'()*+,-./  ␀␁␂␃␄␅␆␇␈␉␊␋␌␍␎␏
 0123456789:;<=>?  ␐␑␒␓␔␕␖␗␘␙␚␛␜␝␞␟
 @ABCDEFGHIJKLMNO  `abcdefghijklmno
 PQRSTUVWXYZ[\]^_  pqrstuvwxyz{|}~␨
 
 Math symbol       Line              Large Character
  √│§∇±∝⌠÷≃ΠΓΨ≡ΦΞ   ┠┨┯┷╟╢╤╧║╂┿─𜸗│┼   𜸚𜸛𜸜𜸝𜸞𜸟𜸠𜸡𜸢𜸣𜸤𜸥𜸦𜸧𜸨
 ⁰¹²³⁴⁵⁶⁷⁸⁹ΩΛ∞⌡☨Σ  ╋┣┫┳┻├┤┬┴═┃━╫𜸖╪╬  𜸩𜸪𜸫𜸬𜸭𜸮𜸯𜸰𜸫𜸱𜸲𜸳𜸴▚𜸵𜸶
 ¶αβψφε∂ληιΘκωμνρ  ╞┗╉█🯎🯏└┘𜸏𜸔𜸐𜸑𜸒╇╈𜸕  𜸷𜸸𜸹𜸺𜸻𜸼𜸽𜸾𜸿𜹀𜹁𜹂𜹃𜹄𜹅𜹆
 πγθστξΔδχυζ↑→Υ←↓  𜸙┏┌┛┐┤╊┓▅𜸘▃╡𜸍╨𜸎╥  𜹇𜹈𜹉𜹊𜹋𜹌𜹍𜹎𜹏𜹐▘▝▖▗▀▌

While I can definitely see why ≃ would be used in Math, I have no idea why HP originally included ☨, but adding one extra character we don't see the real use of to be able to support everything from a whole family of legacy terminals seems to make sense to me with the stated goal of Cozette to provide great coverage of all the glyphs you might encounter in the terminal.
Maybe also adding 🕭 (U+1F56D) to support the same style as the original symbol HP used instead of the generic ␇ control picture)

[PhMajerus]

Characters ≃ and ☨ are now included in PR #144.