* lisp/international/titdic-cnv.el (pinyin-convert):
Enable lexical-binding in the generated file(s).

* lisp/language/ethio-util.el: Use lexical-binding.
(ethio-tex-to-fidel-buffer): Use `inhibit-read-only`.  Remove unused
vars `p` and `ch`.

* lisp/language/hanja-util.el: Use lexical-binding.

* lisp/language/ind-util.el: Use lexical-binding.
(indian-translate-region): Actually use the `from` and `to` arguments.
(<toplevel>): Use `dlet`.  Remove unused var `current-repertory`.
(indian-2-column-to-ucs-region): Remove unused var `pos`.

* lisp/language/japan-util.el: Use lexical-binding.
(japanese-katakana-region, japanese-hiragana-region)
(japanese-zenkaku-region): Remove unused var `next`.

* lisp/language/korea-util.el: Use lexical-binding.

* lisp/language/lao-util.el: Use lexical-binding.
(lao-composition-function): Remove unused var `glyph`.

* lisp/language/thai-util.el: Use lexical-binding.
(thai-composition-function): Remove unused var `glyph`.

* lisp/language/thai-word.el: Use lexical-binding.
(thai-forward-word): Remove unused var `tail`.

* lisp/language/tibet-util.el: Use lexical-binding.
(tibetan-add-components): Remove unused var `tmp`.
(tibetan-compose-region): Remove unused vars `str`, `result`, `chars`.

* lisp/language/viet-util.el:
* lisp/language/tv-util.el:
* lisp/language/cyril-util.el:
* lisp/language/china-util.el: Use lexical-binding.

* lisp/language/tv-util.el (tai-viet-composition-function):
* lisp/language/ethio-util.el (ethio-composition-function):
* lisp/language/japanese.el (compose-gstring-for-variation-glyph):
* lisp/language/thai-util.el (thai-composition-function):
* lisp/language/misc-lang.el (arabic-shape-gstring):
* lisp/language/lao-util.el (lao-composition-function):
* lisp/language/hebrew.el (hebrew-shape-gstring):
* lisp/composite.el (compose-gstring-for-graphic)
(compose-gstring-for-dotted-circle, auto-compose-chars)
(compose-gstring-for-terminal): Accept 2nd argument DIRECTION; all
callers changed.

* src/composite.c (composition_reseat_it): Call
auto-composition-function with one more argument DIRECTION.
(syms_of_composite) <auto-composition-function>: Update the doc
string.
* src/ftfont.c (ftfont_shape_by_hb): Compute language and
direction, and set buffer properties accordingly.
* src/composite.c (autocmp_chars):
* src/w32uniscribe.c (uniscribe_shape):
* src/xftfont.c (xftfont_shape):
* src/ftfont.c (ftfont_shape, ftfont_shape_by_hb):
* src/font.c (Ffont_shape_gstring): Accept an additional argument
DIRECTION.
* src/macfont.m (lgstring_direction): New enum.
(mac_font_shape_1, mac_screen_font_shape, mac_font_shape):
Accept an additional argument specifying text direction.  All
callers changed.
* src/font.c (syms_of_font): New symbols QL2R and QR2L.
* src/font.h (shape): Accept new argument DIRECTION.  All
implementations changed.  (Bug#33729)
(ftfont_shape): Update prototype.

Most of this change is to boilerplate commentary such as license URLs.
This change was prompted by ftp://ftp.gnu.org's going-away party,
planned for November.  Change these FTP URLs to https://ftp.gnu.org
instead.  Make similar changes for URLs to other organizations moving
away from FTP.  Also, change HTTP to HTTPS for URLs to gnu.org and
fsf.org when this works, as this will further help defend against
man-in-the-middle attacks (for this part I omitted the MS-DOS and
MS-Windows sources and the test tarballs to keep the workload down).
HTTPS is not fully working to lists.gnu.org so I left those URLs alone
for now.

This is as per "Tips for Documentation Strings" in the elisp manual.
For consistency, do the same in diagnostics and comments.