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/lib/inlinedform.js

@@ -13,66 +13,66 @@
 //     // the content when the form is close (optional)
 
 // We can only have one inlined form element opened at a time
-currentlyOpenedForm = new ReactiveVar(null);
+const currentlyOpenedForm = new ReactiveVar(null);
 
 InlinedForm = BlazeComponent.extendComponent({
-  template: function() {
+  template() {
     return 'inlinedForm';
   },
 
-  onCreated: function() {
+  onCreated() {
     this.isOpen = new ReactiveVar(false);
   },
 
-  onDestroyed: function() {
+  onDestroyed() {
     currentlyOpenedForm.set(null);
   },
 
-  open: function() {
+  open() {
     // Close currently opened form, if any
     EscapeActions.executeUpTo('inlinedForm');
     this.isOpen.set(true);
     currentlyOpenedForm.set(this);
   },
 
-  close: function() {
+  close() {
     this.isOpen.set(false);
     currentlyOpenedForm.set(null);
   },
 
-  getValue: function() {
-    var input = this.find('textarea,input[type=text]');
+  getValue() {
+    const input = this.find('textarea,input[type=text]');
     return this.isOpen.get() && input && input.value;
   },
 
-  events: function() {
+  events() {
     return [{
       'click .js-close-inlined-form': this.close,
       'click .js-open-inlined-form': this.open,
 
       // Pressing Ctrl+Enter should submit the form
-      'keydown form textarea': function(evt) {
+      'keydown form textarea'(evt) {
         if (evt.keyCode === 13 && (evt.metaKey || evt.ctrlKey)) {
           this.find('button[type=submit]').click();
         }
       },
 
       // Close the inlined form when after its submission
-      submit: function() {
+      submit() {
         if (this.currentData().autoclose !== false) {
           Tracker.afterFlush(() => {
             this.close();
           });
         }
-      }
+      },
     }];
-  }
+  },
 }).register('inlinedForm');
 
 // Press escape to close the currently opened inlinedForm
 EscapeActions.register('inlinedForm',
-  function() { currentlyOpenedForm.get().close(); },
-  function() { return currentlyOpenedForm.get() !== null; }, {
-    noClickEscapeOn: '.js-inlined-form'
+  () => { currentlyOpenedForm.get().close(); },
+  () => { return currentlyOpenedForm.get() !== null; }, {
+    noClickEscapeOn: '.js-inlined-form',
   }
 );