Motion animation export: a study or a joint drive as an animated GIF (#1680)

Thanks @SychPL.

Cargo.toml

@@ -71,6 +71,8 @@ ttf-parser = { version = "0.25", default-features = false, features = ["std"] }
 # images
 image = { version = "0.25", default-features = false, features = ["png", "hdr"] }
 png = "0.18.1"
+# LZW for GIF animations (MIT OR Apache-2.0, pure Rust; already in the tree through image's tiff).
+weezl = "0.1.12"
 
 # ui
 egui = "0.36"