Add router caching. (#248)

* Add router caching.

* Avoid memory leak by limiting cache size.

* Fix search result caching.

* Remove remains of previous player.

Fixes an issue where the spinner/loading from a previous player can show up in a cached page.

src/components/SearchResults.vue

@@ -86,16 +86,13 @@ export default {
     },
     mounted() {
         this.updateResults();
+    },
+    activated() {
         window.addEventListener("scroll", this.handleScroll);
     },
-    unmounted() {
+    deactivated() {
         window.removeEventListener("scroll", this.handleScroll);
     },
-    watch: {
-        "$route.query.search_query": function(q) {
-            if (q) this.updateResults();
-        },
-    },
     methods: {
         async fetchResults() {
             return await await this.fetchJson(this.apiUrl() + "/search", {