Squashed 'external/stb/stb/' changes from c39c7023eb..f4a71b1337

f4a71b1337 README.md: tweak credits
a8a25e17b5 update readme version numbers
0bc88af4de stb_image: optimizations
0ca75da4ec stb_image_resize2: remove whitespace
9d924f8a47 stb_image_resize: 2.04
4da08a1dbd stb_image: create_png_image_raw restructuring
c6d7c32e5d stb_image: Two warning fixes
07268cbf36 stb_image: New Paeth filter
ed64333410 tests: test_png_regress
45eb4ac158 global: very basic .gitignore for object files
e5f0e18d0f stb_image: Small PNG filter simplification
d373674115 stb_image: Fix zlib decoder end-of-stream handling
03f50e343d security notice
1d878bd2a3 security notice
beebb24b94 README.md: fix reference to stb_image_resize2.h
e81f294b16 stb_image_resize: switch GNU/clang from "asm" to "__asm__" for -c99 compatibility
c4bbb6e75f stb_image_resize2.h 2.00
REVERT: c39c7023eb stb_image: create_png_image_raw restructuring
REVERT: 8c3aa05487 stb_image: Two warning fixes
REVERT: 3aa1744a29 stb_image: New Paeth filter
REVERT: 2f3b7e47fa tests: test_png_regress
REVERT: d647af9ad2 global: very basic .gitignore for object files
REVERT: 5a44133dc5 stb_image: Small PNG filter simplification
REVERT: 9f1776a36d stb_image: Fix zlib decoder end-of-stream handling

git-subtree-dir: external/stb/stb
git-subtree-split: f4a71b13373436a2866c5d68f8f80ac6f0bc1ffe

stb_image.h

@@ -1,4 +1,4 @@
-/* stb_image - v2.28 - public domain image loader - http://nothings.org/stb
+/* stb_image - v2.29 - public domain image loader - http://nothings.org/stb
                                   no warranty implied; use at your own risk
 
    Do this:
@@ -48,6 +48,7 @@ LICENSE
 
 RECENT REVISION HISTORY:
 
+      2.29  (2023-05-xx) optimizations
       2.28  (2023-01-29) many error fixes, security errors, just tons of stuff
       2.27  (2021-07-11) document stbi_info better, 16-bit PNM support, bug fixes
       2.26  (2020-07-13) many minor fixes