improving module structure and naming

src/utils.js

@@ -1,6 +1,13 @@
 
 export function noop() {};
 
+// hypotenuse factor of isoscelese right triangle
+export const sqrt2 = Math.sqrt(2);
+
+// short width factor given the lenght of a hexagon's side
+// (2*S gives long width)
+export const sqrt3 = Math.sqrt(3);
+
 export function throttleEvent(type, name, obj) {
 	obj = obj || window;
 	let running = false;
@@ -25,21 +32,16 @@ export function clone(obj) {
 	return JSON.parse(JSON.stringify(obj));
 }
 
-export function extend(obj, src) {
-	for (let key in src) {
-		if (src.hasOwnProperty(key)) obj[key] = src[key];
-	}
+export function extend(obj, ...sources) {
+	sources.forEach(src => {
+		for (let key in src) {
+			if (src.hasOwnProperty(key)) obj[key] = src[key];
+		}
+	});
 
 	return obj;
 }
 
-// hypotenuse factor of isoscelese right triangle
-export let sqrt2 = Math.sqrt(2);
-
-// short width factor given the lenght of a hexagon's side
-// (2*S gives long width)
-export let sqrt3 = Math.sqrt(3);
-
 export function hypotenuse(a, b) {
 	if (b == null) b = a;