Fix geojson-stream integration (#10)

When determining labels, push each label to an empty array, which gets passed back to the through function. This allows us to use  multiple times when there are multiple labels returned from a single feature.

bin/geojson-polygon-labels

@@ -94,7 +94,9 @@ if (includeMinzoom && typeof includeMinzoom === "string" && includeMinzoom.split
 function polylabelStream() {
     return Combiner(geojsonStream.parse(),
         through(function (feature, callback) {
-            this.queue(labelFeature(feature));
+            labelFeature(feature).forEach((feature) => {
+                this.queue(feature);
+            })
         }),
         geojsonStream.stringify());
 }
@@ -106,6 +108,7 @@ inputStream
 
 function labelFeature(inputFeature) {
     featureCount++;
+    let labeledFeatures = [];
     process.stderr.write('...' + featureCount + "\r");
 
     if (inputFeature.geometry) {
@@ -183,8 +186,7 @@ function labelFeature(inputFeature) {
                 if (tippecanoeProperties) {
                     labelFeature.tippecanoe = tippecanoeProperties;
                 }
-                console.log(labelFeature)
-                return labelFeature;
+                labeledFeatures.push(labelFeature);
             }else{
                 if (feature.geometry) {
                     // warn the users that non Polygon features are ignored
@@ -197,6 +199,8 @@ function labelFeature(inputFeature) {
             }
         });
     }
+
+    return labeledFeatures;
 }
 
 function areaToZoom(area, min, max) {