update gamepad inputs to improve attach/detach

dist/preview release/babylon.max.js

@@ -11714,6 +11714,7 @@ var BABYLON;
         };
         FreeCameraGamepadInput.prototype.detachControl = function (element) {
             this._gamepads.dispose();
+            this.gamepad = null;
         };
         FreeCameraGamepadInput.prototype.checkInputs = function () {
             if (this.gamepad) {
@@ -12165,6 +12166,7 @@ var BABYLON;
         };
         ArcRotateCameraGamepadInput.prototype.detachControl = function (element) {
             this._gamepads.dispose();
+            this.gamepad = null;
         };
         ArcRotateCameraGamepadInput.prototype.checkInputs = function () {
             if (this.gamepad) {

src/Cameras/Inputs/babylon.arcrotatecamera.input.gamepad.js

@@ -17,6 +17,7 @@ var BABYLON;
         };
         ArcRotateCameraGamepadInput.prototype.detachControl = function (element) {
             this._gamepads.dispose();
+            this.gamepad = null;
         };
         ArcRotateCameraGamepadInput.prototype.checkInputs = function () {
             if (this.gamepad) {

src/Cameras/Inputs/babylon.arcrotatecamera.input.gamepad.ts

@@ -17,6 +17,7 @@ module BABYLON {
         
         detachControl(element : HTMLElement) {
             this._gamepads.dispose();
+            this.gamepad = null;
         }
 
         checkInputs() {

src/Cameras/Inputs/babylon.freecamera.input.gamepad.js

@@ -17,6 +17,7 @@ var BABYLON;
         };
         FreeCameraGamepadInput.prototype.detachControl = function (element) {
             this._gamepads.dispose();
+            this.gamepad = null;
         };
         FreeCameraGamepadInput.prototype.checkInputs = function () {
             if (this.gamepad) {

src/Cameras/Inputs/babylon.freecamera.input.gamepad.ts

@@ -17,6 +17,7 @@ module BABYLON {
         
         detachControl(element : HTMLElement){
             this._gamepads.dispose();
+            this.gamepad = null;
         }
         
         checkInputs(){