Introduce subscription::Event

... and remove `PlatformSpecific` from `Event`

examples/url_handler/src/main.rs

@@ -1,4 +1,4 @@
-use iced::event::{self, Event};
+use iced::event;
 use iced::widget::{center, text};
 use iced::{Element, Subscription};
 
@@ -15,27 +15,20 @@ struct App {
 
 #[derive(Debug, Clone)]
 enum Message {
-    EventOccurred(Event),
+    UrlReceived(String),
 }
 
 impl App {
     fn update(&mut self, message: Message) {
         match message {
-            Message::EventOccurred(event) => {
-                if let Event::PlatformSpecific(
-                    event::PlatformSpecific::MacOS(event::MacOS::ReceivedUrl(
-                        url,
-                    )),
-                ) = event
-                {
-                    self.url = Some(url);
-                }
+            Message::UrlReceived(url) => {
+                self.url = Some(url);
             }
         }
     }
 
     fn subscription(&self) -> Subscription<Message> {
-        event::listen().map(Message::EventOccurred)
+        event::listen_url().map(Message::UrlReceived)
     }
 
     fn view(&self) -> Element<Message> {