Cgohlke

- Add GIF codec via giflib.
- Add TIFF decoder via libtiff.
- Add codec_check functions.
- Fix formatting libjpeg error messages.
- Use xfail in tests.
- Load extensions on demand on Python >= 3.7.
- Add build options to skip building specific extensions.
- Split imagecodecs extension into individual extensions.
- Move shared code into shared extension.
- Rename imagecodecs_lite extension and imagecodecs C library to 'imcd'.
- Remove support for Python 2.7 and 3.5.

- Fix reading MCS_BLOCK data.
- Remove support for Python 2.7 and 3.5.
- Update copyright.

- Fix decoding of indexed PNG with transparency.
- Last version to support Python 2.7 and 3.5.

- Add Zopfli codec.
- Add Snappy codec.
- Rename j2k codec to jpeg2k.
- Rename jxr codec to jpegxr.
- Use Debian's jxrlib.
- Support pathlib and binary streams in imread and imwrite.
- Move external C declarations to pxd files.
- Move shared code to pxi file.
- Update copyright notices.

- Add version functions.
- Add Brotli codec.
- Add optional JPEG XL codec via Brunsli repacker.

- Sync with imagecodecs-lite.