Make choropleth mode work with lines

umap/static/umap/js/umap.features.js

@@ -948,6 +948,7 @@ L.U.Polyline = L.Polyline.extend({
   staticOptions: {
     stroke: true,
     fill: false,
+    mainColor: 'color',
   },
 
   isSameClass: function (other) {

umap/static/umap/js/umap.layer.js

@@ -132,7 +132,7 @@ L.U.Layer.Choropleth = L.FeatureGroup.extend({
 
   _getValue: function (feature) {
     const key = this.datalayer.options.choropleth.property || 'value'
-    return feature.properties[key]
+    return +feature.properties[key] // TODO: should we catch values non castable to int ?
   },
 
   computeLimits: function () {