Format/library/license overview

[maia-s]

I made an overview over which formats are supported by which backends and what libraries they bring in/depend on. Can it be added to the docs somewhere?

Notes:

• If backends STB/WIC/ImageIO are used, libraries aren't used for formats they support
• ImageIO overrides built-in for supported formats
• QOI is the only built-in format that isn't Zlib licensed
• AVIF and JXL have a lot of dependencies with different licenses that are hard to work out

(License ids are in SPDX format)

Format	Built-in	STB	WIC	ImageIO	Library
avif					libavif (BSD-2-Clause) + aom (BSD-2-Clause) + dav1d (BSD-2-Clause) + ...
bmp	✅			✅
gif	✅			✅
jpg		✅	✅	✅	libjpeg (IJG-short)
jxl					libjxl (BSD-3-Clause) + ...
lbm	✅
pcx	✅
png		✅	✅	✅	libpng (Libpng) + libz (Zlib)
pnm	✅
qoi	✅ (MIT)
svg	✅
tga	✅			✅
tif			✅	✅	libtiff (libtiff)
webp					libwebp (BSD-3-Clause)
xcf	✅
xpm	✅
xv	✅

| Format | Built-in | STB | WIC | ImageIO | Library |
| ------ | :------: | :-: | :-: | :-----: | ------- |
| avif   |          |     |     |         | libavif (BSD-2-Clause) + aom (BSD-2-Clause) + dav1d (BSD-2-Clause) + ... |
| bmp    | ✅       |     |     | ✅       |         |
| gif    | ✅       |     |     | ✅       |         |
| jpg    |          | ✅  | ✅  | ✅       | libjpeg (IJG-short) |
| jxl    |          |     |     |         | libjxl (BSD-3-Clause) + ... |
| lbm    | ✅       |     |     |         |         |
| pcx    | ✅       |     |     |         |         |
| png    |          | ✅  | ✅  | ✅       | libpng (Libpng) + libz (Zlib) |
| pnm    | ✅       |     |     |         |         |
| qoi    | ✅ (MIT) |     |     |         |         |
| svg    | ✅       |     |     |         |         |
| tga    | ✅       |     |     | ✅      |         |
| tif    |          |     | ✅  | ✅      | libtiff (libtiff) |
| webp   |          |     |     |         | libwebp (BSD-3-Clause) |
| xcf    | ✅       |     |     |         |         |
| xpm    | ✅       |     |     |         |         |
| xv     | ✅       |     |     |         |         |