Registry refactor and clear queues on board entry

kiln-core/src/api/queue.rs

@@ -73,13 +73,17 @@ impl ObjQueue {
     pub fn waiting(&mut self) -> bool {
         matches!(self.0.borrow().front(), Some(Action::Delay(_)))
     }
+
+    pub fn clear(&mut self) {
+        self.0.borrow_mut().clear();
+    }
 }
 
 impl Registerable for ObjQueue {
     fn register(engine: &mut Engine, error_sink: ErrorSink) {
         engine.register_type_with_name::<ObjQueue>("Queue");
         engine.register_get("length", |q: &mut ObjQueue| q.0.borrow().len() as i64);
-        engine.register_fn("clear", |q: &mut ObjQueue| q.0.borrow_mut().clear());
+        engine.register_fn("clear", ObjQueue::clear);
 
         // Appends a [`Action::Delay`] to the back of `queue`, merging with an existing
         // trailing delay to prevent adjacent delays from accumulating.