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/session.js

@@ -30,7 +30,7 @@ class Session{
 			}else if(response.type === "songsel"){
 				p2.clearMessage("users")
 				this.onEnd(false, true)
-				pageEvents.send("session-start")
+				pageEvents.send("session-start", "host")
 			}
 		})
 		p2.send("invite")