feat: re-export image crate

`RasterRenderer::render` returns an `image::ImageRgba` so it's only fair
that users have access to a proper version of `image` without having to
keep track of it themselves.

src/lib.rs

@@ -42,6 +42,8 @@
     unused_qualifications
 )]
 
+pub use image;
+
 pub use hand::*;
 
 mod hand;