Fixed problems with "retain filter" memory.

- eslint issues
- hidden checkboxes were not toggling correctly, so functionality was broken

themes/bootstrap3/js/common.js

@@ -363,10 +363,12 @@ $(document).ready(function commonDocReady() {
   $('.facet.list-group .collapse').on('hidden.bs.collapse', facetSessionStorage);
 
   // retain filter sessionStorage
-  $('.searchFormKeepFilters').click(function() {
-    sessionStorage.setItem('vufind_retain_filters', this.checked);
+  $('.searchFormKeepFilters').click(function retainFiltersInSessionStorage() {
+    sessionStorage.setItem('vufind_retain_filters', this.checked ? 'true' : 'false');
   });
   if (sessionStorage.getItem('vufind_retain_filters')) {
-    $('.searchFormKeepFilters').prop('checked', sessionStorage.getItem('vufind_retain_filters') == 'true');
+    var state = (sessionStorage.getItem('vufind_retain_filters') === 'true');
+    $('.searchFormKeepFilters').prop('checked', state);
+    $('.applied-filter').prop('checked', state);
   }
 });