Added RandomDataGenerator.sign (returns -1 or +1)

Author: taylankasap

src/math/RandomDataGenerator.js

@@ -268,6 +268,18 @@ Phaser.RandomDataGenerator.prototype = {
 
     },
 
+    /**
+    * Returns a sign to be used with multiplication operator.
+    *
+    * @method Phaser.RandomDataGenerator#sign
+    * @return {number} -1 or +1.
+    */
+    sign: function () {
+
+        return this.pick([-1, 1]);
+
+    },
+
     /**
     * Returns a random member of `array`, favoring the earlier entries.
     *