client/paging: fix endless scroll return path

Since some refactors it has always been returning to page 1.

client/js/main.js

@@ -12,7 +12,7 @@ router.exit(
     (ctx, next) => {
         ctx.state.scrollX = window.scrollX;
         ctx.state.scrollY = window.scrollY;
-        ctx.save();
+        router.replace(router.url, ctx.state);
         if (misc.confirmPageExit()) {
             next();
         }

client/js/router.js

@@ -6,6 +6,8 @@
 // - simplified method chains
 // - added ability to call .save() in .exit() without side effects
 // - page refresh recovers state from history
+// - rename .save() to .replaceState()
+// - offer .url
 
 const pathToRegexp = require('path-to-regexp');
 const clickEvent = document.ontouchstart ? 'touchstart' : 'click';
@@ -47,7 +49,7 @@ class Context {
         history.pushState(this.state, this.title, this.canonicalPath);
     }
 
-    save() {
+    replaceState() {
         history.replaceState(this.state, this.title, this.canonicalPath);
     }
 };
@@ -149,10 +151,10 @@ class Router {
         var ctx = new Context(path, state);
         if (dispatch) {
             this.dispatch(ctx, () => {
-                ctx.save();
+                ctx.replaceState();
             });
         } else {
-            ctx.save();
+            ctx.replaceState();
         }
         return ctx;
     }
@@ -184,6 +186,10 @@ class Router {
         router.stop();
         location.href = ctx.canonicalPath;
     }
+
+    get url() {
+        return location.pathname + location.search + location.hash;
+    }
 };
 
 const _onPopState = router => {

client/js/views/endless_page_view.js

@@ -65,7 +65,7 @@ class EndlessPageView {
         if (topPageNumber !== this.currentPage) {
             router.replace(
                 ctx.getClientUrlForPage(topPageNumber),
-                {},
+                ctx.state,
                 false);
             this.currentPage = topPageNumber;
         }

client/js/views/posts_header_view.js

@@ -110,7 +110,7 @@ class PostsHeaderView {
         browsingSettings.listPosts[safety] =
             !browsingSettings.listPosts[safety];
         settings.save(browsingSettings, true);
-        router.show(location.pathname + location.search + location.hash);
+        router.show(router.url);
     }
 
     _evtSearchFormSubmit(e) {