Expose the client's requesting URL to apps.

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@4374 ed5197a5-7fde-0310-b194-c3ffbd925b24

core/client.js

@@ -1072,6 +1072,7 @@ function connectSocket(path) {
 			gSocket.send(JSON.stringify({
 				action: "hello",
 				path: connect_path,
+				url: window.location.href,
 				api: Object.entries(k_api).map(([key, value]) => [].concat([key], value.args)),
 			}));
 		}