Preserve history state when updating hash

Current implementation replaces history state on every moveend with empty string.

The purposed solution replaces state with current state instead of empty string. The reason for this is to let other code to use history state as it is usual for single page applications.

src/ui/hash.js

@@ -91,7 +91,7 @@ class Hash {
 
     _updateHashUnthrottled() {
         const hash = this.getHashString();
-        window.history.replaceState('', '', hash);
+        window.history.replaceState(window.history.state, '', hash);
     }
 
 }