Make hWnd: HWND public

[NikolayJuly]

Right now View has internal var hWnd: HWND!. And If I want to make some extension, like DirectX rendering view, I can't integrate it with this frmaework. If make it public, I can create view and use it as target for DirectX rendering.
Any other changes, like adding new view subclasses, might also need access to hWnd if I need to make changes using native windows code.