D support: Add D support in the tools.

D support: Add D support in the tools.

* autopull.sh: Check out tree-sitter-d. Set TREE_SITTER_D_VERSION.
* autogen.sh (GNULIB_MODULES_TOOLS_FOR_SRC): Add unistr/u16-check,
unistr/u16-to-u8, unistr/u32-check, unistr/u32-to-u8.
* gettext-tools/build-aux/tree-sitter-d-portability.diff: New file.
* gettext-tools/configure.ac: Set TREE_SITTER_D_VERSION.
* gettext-tools/Makefile.am (EXTRA_DIST): Add the tree-sitter-d source code and
patch.
* gettext-tools/doc/lang-d.texi: New file.
* gettext-tools/doc/Makefile.am (gettext_TEXINFOS): Add it.
* gettext-tools/doc/gettext.texi (PO Files): Mention d-format.
(No string concatenation): Mention string concatenation and string interpolation
in D.
(Translators for other Languages): New subsection "D Format Strings".
(List of Programming Languages): Include lang-d.texi.
* gettext-tools/doc/xgettext.texi: Document the -L D option.
* gettext-tools/src/message.h (format_d): New enum value.
(NFORMATS): Increment.
* gettext-tools/src/message.c (format_language, format_language_pretty): Add an
entry for format_d.
* gettext-tools/src/format-d.c: New file, based on
gettext-tools/src/format-lisp.c.
* gettext-tools/src/format.h (formatstring_d): New declaration.
* gettext-tools/src/format.c (formatstring_parsers): Add formatstring_d.
* gettext-tools/src/x-d.h: New file.
* gettext-tools/src/x-d.c: New file, based on gettext-tools/src/x-rust.c and
gettext-tools/src/x-go.c.
* gettext-tools/src/html5-entities.h: New file.
* gettext-tools/src/xgettext.c: Include x-d.h.
(flag_table_d): New variable.
(main): Invoke init_flag_table_d, x_d_extract_all, x_d_keyword.
(usage): Document the -L D option.
(xgettext_record_flag): Support format_d.
(language_to_extractor, extension_to_language): Support D.
* gettext-tools/src/xg-message.c (decide_is_format, remember_a_message_plural):
Add better heuristic for c-format and d-format.
* gettext-tools/src/FILES: Mention format-d.c, x-d.h, x-d.c, html5-entities.h.
* gettext-tools/src/Makefile.am (noinst_HEADERS): Add x-d.h, html5-entities.h.
(FORMAT_SOURCE): Add format-d.c.
(libxgettextts2_a_SOURCES): Add d-parser.c, d-scanner.c.
(xgettext_SOURCES): Add x-d.c.
* gettext-tools/libgettextpo/Makefile.am (libgettextpo_la_AUXSOURCES): Add
format-d.c.
* gettext-tools/po/POTFILES.in: Add src/format-d.c, src/x-d.c.
* gettext-tools/woe32dll/gettextsrc-exports.c: Export formatstring_d.
* gettext-tools/tests/format-d-1: New file.
* gettext-tools/tests/format-d-2: New file.
* gettext-tools/tests/xgettext-d-1: New file.
* gettext-tools/tests/xgettext-d-2: New file.
* gettext-tools/tests/xgettext-d-3: New file.
* gettext-tools/tests/xgettext-d-4: New file.
* gettext-tools/tests/xgettext-d-5: New file, based on
gettext-tools/tests/xgettext-rust-5.
* gettext-tools/tests/xgettext-d-6: New file, based on
gettext-tools/tests/xgettext-rust-7.
* gettext-tools/tests/testdata/dprog.utf-8.d: New file.
* gettext-tools/tests/testdata/dprog.utf-8+bom.d: New file, based on
gettext-tools/tests/testdata/dprog.utf-8.d.
* gettext-tools/tests/testdata/dprog.utf-16be.d: New file, based on
gettext-tools/tests/testdata/dprog.utf-8.d.
* gettext-tools/tests/testdata/dprog.utf-16le.d: New file, based on
gettext-tools/tests/testdata/dprog.utf-8.d.
* gettext-tools/tests/testdata/dprog.utf-32be.d: New file, based on
gettext-tools/tests/testdata/dprog.utf-8.d.
* gettext-tools/tests/testdata/dprog.utf-32le.d: New file, based on
gettext-tools/tests/testdata/dprog.utf-8.d.
* gettext-tools/tests/Makefile.am (TESTS): Add the new tests.
(EXTRA_DIST): Add the new testdata files.
* NEWS: Mention the D support.