Enforce a consistent ES6 coding style

Replace the old (and broken) jshint + jscsrc by eslint and configure
it to support some of the ES6 features.

The command `eslint` currently has one error which is a bug that was
discovered by its static analysis and should be fixed (usage of a
dead object).

client/components/lists/listHeader.js

@@ -1,78 +1,78 @@
 BlazeComponent.extendComponent({
-  template: function() {
+  template() {
     return 'listHeader';
   },
 
-  editTitle: function(evt) {
+  editTitle(evt) {
     evt.preventDefault();
-    var form = this.componentChildren('inlinedForm')[0];
-    var newTitle = form.getValue();
+    const form = this.componentChildren('inlinedForm')[0];
+    const newTitle = form.getValue();
     if ($.trim(newTitle)) {
       Lists.update(this.currentData()._id, {
         $set: {
-          title: newTitle
-        }
+          title: newTitle,
+        },
       });
     }
   },
 
-  events: function() {
+  events() {
     return [{
       'click .js-open-list-menu': Popup.open('listAction'),
-      submit: this.editTitle
+      submit: this.editTitle,
     }];
-  }
+  },
 }).register('listHeader');
 
 Template.listActionPopup.events({
-  'click .js-add-card': function() {
-    var listDom = document.getElementById('js-list-' + this._id);
-    var listComponent = BlazeComponent.getComponentForElement(listDom);
+  'click .js-add-card'() {
+    const listDom = document.getElementById(`js-list-${this._id}`);
+    const listComponent = BlazeComponent.getComponentForElement(listDom);
     listComponent.openForm({ position: 'top' });
     Popup.close();
   },
-  'click .js-list-subscribe': function() {},
-  'click .js-select-cards': function() {
-    var cardIds = Cards.find(
+  'click .js-list-subscribe'() {},
+  'click .js-select-cards'() {
+    const cardIds = Cards.find(
       {listId: this._id},
       {fields: { _id: 1 }}
-    ).map(function(card) { return card._id; });
+    ).map((card) => card._id);
     MultiSelection.add(cardIds);
     Popup.close();
   },
   'click .js-move-cards': Popup.open('listMoveCards'),
-  'click .js-archive-cards': Popup.afterConfirm('listArchiveCards', function() {
-    Cards.find({listId: this._id}).forEach(function(card) {
+  'click .js-archive-cards': Popup.afterConfirm('listArchiveCards', () => {
+    Cards.find({listId: this._id}).forEach((card) => {
       Cards.update(card._id, {
         $set: {
-          archived: true
-        }
+          archived: true,
+        },
       });
     });
     Popup.close();
   }),
-  'click .js-close-list': function(evt) {
+  'click .js-close-list'(evt) {
     evt.preventDefault();
     Lists.update(this._id, {
       $set: {
-        archived: true
-      }
+        archived: true,
+      },
     });
     Popup.close();
-  }
+  },
 });
 
 Template.listMoveCardsPopup.events({
-  'click .js-select-list': function() {
-    var fromList = Template.parentData(2).data._id;
-    var toList = this._id;
-    Cards.find({listId: fromList}).forEach(function(card) {
+  'click .js-select-list'() {
+    const fromList = Template.parentData(2).data._id;
+    const toList = this._id;
+    Cards.find({ listId: fromList }).forEach((card) => {
       Cards.update(card._id, {
         $set: {
-          listId: toList
-        }
+          listId: toList,
+        },
       });
     });
     Popup.close();
-  }
+  },
 });