feat(SDK): ability to synchronise the play area transform on sdk switch

A new checkbox on the SDK Setup Switcher that when checked will
synchronise the play area transform to the previous play area transform
when the SDK is switched.

This is useful when wanting to move the play area around with the
Simulator and then switch to an SDK of an actual HMD and be in the
position of where the Simulator was moved to.

Author: thestonefox

Assets/VRTK/Source/Scripts/Utilities/SDK/VRTK_SDKSetupSwitcher.cs

@@ -38,6 +38,8 @@ public class VRTK_SDKSetupSwitcher : MonoBehaviour
         private Button cancelButton;
         [SerializeField]
         private Button chooseButton;
+        [SerializeField]
+        private bool playareaSync = true;
 
         protected enum ViewingState
         {
@@ -47,6 +49,7 @@ protected enum ViewingState
 
         private VRTK_SDKManager sdkManager;
         private readonly List<GameObject> chooseButtonGameObjects = new List<GameObject>();
+        private Transform currentPlayarea;
 
         protected virtual void Awake()
         {
@@ -79,6 +82,14 @@ protected virtual void OnDisable()
         protected virtual void OnLoadedSetupChanged(VRTK_SDKManager sender, VRTK_SDKManager.LoadedSetupChangeEventArgs e)
         {
             Show(ViewingState.Status);
+            if (playareaSync && currentPlayarea != null)
+            {
+                Transform newPlayarea = VRTK_DeviceFinder.PlayAreaTransform();
+                newPlayarea.transform.position = currentPlayarea.transform.position;
+                newPlayarea.transform.rotation = currentPlayarea.transform.rotation;
+                VRTK_SharedMethods.SetGlobalScale(newPlayarea, currentPlayarea.transform.lossyScale);
+            }
+            currentPlayarea = VRTK_DeviceFinder.PlayAreaTransform();
         }
 
         protected virtual void OnSwitchButtonClick()
@@ -130,7 +141,7 @@ protected virtual void AddSelectionButtons()
             VRTK_SDKSetup loadedSetup = sdkManager.loadedSetup;
             if (loadedSetup != null)
             {
-                GameObject chooseNoneButton = (GameObject)Instantiate(chooseButton.gameObject, chooseButton.transform.parent);
+                GameObject chooseNoneButton = Instantiate(chooseButton.gameObject, chooseButton.transform.parent);
                 chooseNoneButton.GetComponentInChildren<Text>().text = "None";
                 chooseNoneButton.name = "ChooseNoneButton";
                 chooseNoneButton.SetActive(true);
@@ -151,7 +162,7 @@ protected virtual void AddSelectionButtons()
                     continue;
                 }
 
-                GameObject chooseButtonCopy = (GameObject)Instantiate(chooseButton.gameObject, chooseButton.transform.parent);
+                GameObject chooseButtonCopy = Instantiate(chooseButton.gameObject, chooseButton.transform.parent);
                 chooseButtonCopy.GetComponentInChildren<Text>().text = setup.name;
                 chooseButtonCopy.name = string.Format("Choose{0}Button", setup.name);
                 chooseButtonCopy.SetActive(true);