Add num-images and heap-in-use fields to /about

store/store.go

@@ -117,3 +117,10 @@ func Save(data []byte, contentType string) string {
 	}
 	return store.Save(data, contentType)
 }
+
+func NumImages() int {
+	if store == nil {
+		store = newStore()
+	}
+	return len(store.images)
+}