File sizes of screencasts should be smaller now

If you have at least 4 CPU cores, encoding will be faster.

• -o - writes to stdout, which may help with scripting and integration with non-C/Rust environments.
• fixed outdated struct definition in gifski.h.

The GIF format is very weird with handling of transparency. Issues with white or green artifacts and cropped top/bottom of frames should be fixed now.

• Identical frames are merged together (skipped)
• More video decoding improvements
• Lossy GIF compression is enabled by default when using quality < 100
• gifski will automatically downscale videos that are too large for GIF (sorry, codec from 1989 is not for 4K videos)

Binaries for macOS and Debian now come with video support built-in. (Sorry, there's still no video support on Windows, because Visual Studio compiler and tooling are still such a pain.)

cargo install gifski --features=video

Is now supported as well.

• Improved handling of fps.
• Fixed dithering bug.
• Quality setting uses lossy LZW.