Use blocked scoped variables

In addition to using const and let, this also upgrades our linter config and removes lint (mostly whitespace).

examples/kml.js

@@ -6,21 +6,21 @@ import VectorLayer from '../src/ol/layer/Vector.js';
 import BingMaps from '../src/ol/source/BingMaps.js';
 import VectorSource from '../src/ol/source/Vector.js';
 
-var raster = new TileLayer({
+const raster = new TileLayer({
   source: new BingMaps({
     imagerySet: 'Aerial',
     key: 'As1HiMj1PvLPlqc_gtM7AqZfBL8ZL3VrjaS3zIb22Uvb9WKhuJObROC-qUpa81U5'
   })
 });
 
-var vector = new VectorLayer({
+const vector = new VectorLayer({
   source: new VectorSource({
     url: 'data/kml/2012-02-10.kml',
     format: new KML()
   })
 });
 
-var map = new Map({
+const map = new Map({
   layers: [raster, vector],
   target: document.getElementById('map'),
   view: new View({
@@ -30,14 +30,14 @@ var map = new Map({
   })
 });
 
-var displayFeatureInfo = function(pixel) {
-  var features = [];
+const displayFeatureInfo = function(pixel) {
+  const features = [];
   map.forEachFeatureAtPixel(pixel, function(feature) {
     features.push(feature);
   });
   if (features.length > 0) {
-    var info = [];
-    var i, ii;
+    const info = [];
+    let i, ii;
     for (i = 0, ii = features.length; i < ii; ++i) {
       info.push(features[i].get('name'));
     }
@@ -53,7 +53,7 @@ map.on('pointermove', function(evt) {
   if (evt.dragging) {
     return;
   }
-  var pixel = map.getEventPixel(evt.originalEvent);
+  const pixel = map.getEventPixel(evt.originalEvent);
   displayFeatureInfo(pixel);
 });