Fixed Math.atan2 arguments in wrong order

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/atan2

Author: jotson

src/geom/Line.js

@@ -207,7 +207,7 @@ Object.defineProperty(Phaser.Line.prototype, "length", {
 Object.defineProperty(Phaser.Line.prototype, "angle", {
 
     get: function () {
-        return Math.atan2(this.end.x - this.start.x, this.end.y - this.start.y);
+        return Math.atan2(this.end.y - this.start.y, this.end.x - this.start.x);
     }
 
 });

src/math/Math.js

@@ -336,7 +336,7 @@ Phaser.Math = {
     * @return {number}
     */
     angleBetween: function (x1, y1, x2, y2) {
-        return Math.atan2(x2 - x1, y2 - y1);
+        return Math.atan2(y2 - y1, x2 - x1);
     },
 
     /**
@@ -347,7 +347,7 @@ Phaser.Math = {
     * @return {number}
     */
     angleBetweenPoints: function (point1, point2) {
-        return Math.atan2(point2.x - point1.x, point2.y - point1.y);
+        return Math.atan2(point2.y - point1.y, point2.x - point1.x);
     },
 
     /**