consistent query parameter handling between client and server - fixes #497

test/apps/basics/src/routes/echo-query/index.html

@@ -1,9 +1 @@
-<h1>message: "{message}"</h1>
-
-<script>
-	export default {
-		preload({ query }) {
-			return query;
-		}
-	};
-</script>
+<h1>{JSON.stringify(query)}</h1>

test/apps/basics/src/routes/index.html

@@ -3,5 +3,6 @@
 <a href="a">a</a>
 <a href="ambiguous/ok.json">ok</a>
 <a href="echo-query?message">ok</a>
+<a href="echo-query?p=one&p=two">ok</a>
 
 <div class='hydrate-test'></div>