wasm-bindgen-rayon and new OMT plugin (#1007)

* WIP: wasm-bindgen-rayon and new OMT plugin

* Bump package-lock

* Make OMT work again

* Update year

* Restore accidental change

* Prevent minification of `nextDefineUri`

* Delay loading external deps

This gives inline `define` calls a chance to define dependencies for earlier `define` calls on the same page.

* Add comment

codecs/oxipng/src/lib.rs

@@ -1,9 +1,9 @@
+#[cfg(feature = "parallel")]
+pub use wasm_bindgen_rayon::init_thread_pool;
+
 use oxipng::AlphaOptim;
 use wasm_bindgen::prelude::*;
 
-#[cfg(feature = "parallel")]
-pub mod parallel;
-
 #[wasm_bindgen]
 pub fn optimise(data: &[u8], level: u8) -> Vec<u8> {
     let mut options = oxipng::Options::from_preset(level);