Rename scheduling to 'async_io', general cleanup

libk/src/std/application.rs

@@ -7,7 +7,10 @@ mod window;
 pub trait Application {
     type Output;
 
-    async fn run(&mut self, args: Vec<String>) -> Result<Self::Output, Error>;
+    fn run(
+        &mut self,
+        args: Vec<String>,
+    ) -> impl core::future::Future<Output = Result<Self::Output, Error>> + Send;
 }
 
 #[derive(Debug)]

libk/src/std/io/mod.rs

@@ -1,2 +0,0 @@
-mod io;
-pub use io::*;