Remove unused subsystem module.

src/lib.rs

@@ -35,4 +35,4 @@ pub mod player;
 pub mod session;
 pub mod spirc;
 pub mod stream;
-pub mod subsystem;
+

src/subsystem.rs

@@ -1,9 +0,0 @@
-use std::thread;
-
-pub trait Subsystem : Send + Sized + 'static {
-    fn run(self);
-    fn start(self) {
-        thread::spawn(move || self.run());
-    }
-}
-