Skia backend for egui

This is a drawing backend for egui that uses skia-safe.

Usage

Have a look at the metal or cpu examples to get started.

Run the examples

```bash cargo run --example metal --features winit,metal cargo run --example cpu --features winit,cpufix cargo run --example rasterize --features winit,cpufix

Make sure sdl2 is installed

Follow instructions here: https://github.com/Rust-SDL2/rust-sdl2

cargo run --example sdl2opengl --features gl cargo run --example sdl2vulkan --features vulkan ```

Status

Rendering on the gpu works great, only the dancing strings example doesn't work for some reason.

For rendering on the cpu to look correct, the cpufix feature needs to be enabled. See https://github.com/lucasmerlin/eguiskia/issues/1 for more information.

Preview:

https://user-images.githubusercontent.com/8009393/184211263-13d1f2d5-0125-4187-98a6-e95f003e7e75.mov