whiteSpace default value change to undefined (#3782)

TKUnit default message change to empty string
isSet method is now instance method of Property classes
fix detaching from parent bindingContext - were using oldParent.parent instead of parent
editable-text-base.android - onTextChanged implementation commented. Does nothing.
frame - onCreateView wrapped in try/catch and shows label with exception message if any
text-base.android - should support reset of nativeView. TransformationMethod won’t be set if TextField is secure
Change some types to their string couterparts
TextField.android won’t support multilines anymore in order to work as iOS
In android when page is removed from native backstack we won’t call tearDownUI again a second time

tns-core-modules/ui/button/button.android.ts

@@ -1,6 +1,7 @@
 import {
     ButtonBase, PseudoClassHandler,
-    paddingLeftProperty, paddingTopProperty, paddingRightProperty, paddingBottomProperty, Length, zIndexProperty
+    paddingLeftProperty, paddingTopProperty, paddingRightProperty, paddingBottomProperty, 
+    Length, zIndexProperty
 } from "./button-common";
 
 import { TouchGestureEventData, GestureTypes, TouchAction } from "../gestures";
@@ -35,16 +36,13 @@ function initializeClickListener(): void {
 
 export class Button extends ButtonBase {
     _button: android.widget.Button;
+    
     private _highlightedHandler: (args: TouchGestureEventData) => void;
 
-    get android(): android.widget.Button {
-        return this._button;
-    }
-
     public _createNativeView() {
         initializeClickListener();
         const button = this._button = new android.widget.Button(this._context);
-        this._button.setOnClickListener(new ClickListener(this));
+        button.setOnClickListener(new ClickListener(this));
         return button;
     }