bug#66614: 29.1.50; Support not capitalizing words inside symbols

[Eli Zaretskii <eliz@gnu.org>]

> From: Spencer Baugh <sbaugh@janestreet.com>
> Date: Wed, 18 Oct 2023 13:01:43 -0400
> 
> >From e11c5096b2e0a3eddec8fac692142ff31c889109 Mon Sep 17 00:00:00 2001
> From: Spencer Baugh <sbaugh@janestreet.com>
> Date: Wed, 18 Oct 2023 12:51:37 -0400
> Subject: [PATCH] Add case-symbols-as-words to configure symbol case behavior
> 
> In some programming languages and styles, a symbol (or every symbol in
> a sequence of symbols) might be capitalized, but the individual words
> making up the symbol should never be capitalized.
> 
> For example, in OCaml, type names Look_like_this and variable names
> look_like_this, but it is basically never correct for something to
> Look_Like_This.  And one might have "aa_bb cc_dd ee_ff" or "Aa_bb
> Cc_dd Ee_ff", but never "Aa_Bb Cc_Dd Ee_Ff".
> 
> To support this, the new variable case-symbols-as-words causes symbol
> constituents to be treated as part of words only for case operations.
> 
> * src/casefiddle.c (case_ch_is_word): Add.
> (case_character_impl): Use case_ch_is_word.
> (case_character): Use case_ch_is_word.
> (syms_of_casefiddle): Define case-symbols-as-words. (bug#66614)
> * src/search.c (Freplace_match): Use case-symbols-as-words when
> calculating case pattern.
> * test/src/casefiddle-tests.el (casefiddle-tests--check-syms)
> (casefiddle-case-symbols-as-words): Test case-symbols-as-words.
> * etc/NEWS: Announce case-symbols-as-words.
> * doc/lispref/strings.texi (Case Conversion): Document
> case-symbols-as-words.

Stefan, any comments?