lib: Add default impl for state ticker

examples/basic.rs

@@ -45,8 +45,6 @@ impl store::State<()> for State {
             }
         }
     }
-
-    fn tick(&mut self) {}
 }
 
 #[tokio::main]

examples/hello.rs

@@ -44,8 +44,6 @@ impl store::State<()> for State {
             Message::Quit => Some(Exit { value: None }),
         }
     }
-
-    fn tick(&mut self) {}
 }
 
 #[tokio::main]

src/store.rs

@@ -24,7 +24,7 @@ where
     fn update(&mut self, message: Self::Message) -> Option<Exit<P>>;
 
     /// Handle recurring tick.
-    fn tick(&mut self);
+    fn tick(&mut self) {}
 }
 
 /// The `Store` updates the applications' state concurrently. It handles