* fixing issue 921

* using Robert's idea

* faster amalgamation script

* more optimization

* adding short input benchmarks

* lint

* broader coverage

* silencing

* adding script.

* optimise simdutf for short strings

* lint

* sorting headers

* adding documentation.

* update readme

* undo unwanted merge

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Co-authored-by: sleepingieght <[email protected]>

* the get_default_implementation and get_single_implementation should be
inlined, for best performance.

* saving.

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Co-authored-by: Daniel Lemire <[email protected]>

Co-authored-by: Daniel Lemire <[email protected]>

* actually benchmark simdutf::find

* lint

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Co-authored-by: Daniel Lemire <[email protected]>

* add convert_utf16_to_utf8_with_replacement

* lint

* use to_utf16le for input in surrogate pair tests

* Update tests/convert_utf16_to_utf8_with_replacement_tests.cpp

* add constexpr test

* lint

* use output size

* add AI policy

* Add transparency guidelines for AI-assisted contributions

Added a section on transparency regarding AI assistance in contributions.

Clarified support policy for obsolete compilers and tools.

Uses `simdutf_constexpr if` to let the compiler know which branch will never be executed to avoid emitting of the `-Warray-bounds` warning on code paths that would do an out of bounds array access.

* Optimized base64 length function for most kernels

Co-authored-by: Erik Corry <[email protected]>

* Optimized base64 length function for most kernels : most files

Co-authored-by: Erik Corry <[email protected]>

* missing operators for loongson

* went too far

* doing it differently.

* various tweaks to ppc64

* lint

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Co-authored-by: Erik Corry <[email protected]>