Change some events, fix p2 sending gameend twice

- Fixed gameend being sent twice in p2
- Add `ready`, `loader-error`, and `song-select-random` events
- Fixed `session-start` not firing when invited, added event detail
- Fixed `language-change` being fired at startup
- Fixed `version-link` and `about-link` firing twice
- "#song=" will fire `song-select-difficulty`
- Removed `key-events` and `scoresheet-player2`, merged with `scoresheet` and made it more detailed

public/src/js/about.js

@@ -152,8 +152,10 @@
 		return target.getElementsByTagName("a")[0]
 	}
 	linkButton(event){
-		this.getLink(event.currentTarget).click()
-		pageEvents.send("about-link", event)
+		if(event.target === event.currentTarget){
+			this.getLink(event.currentTarget).click()
+			pageEvents.send("about-link", event)
+		}
 	}
 	clean(){
 		cancelTouch = true