title: MvvmCross ViewModel lifecycle during rotation
body: <p>I have been using Mvvmcross to develop Android application. I am dealing with the issue of ViewModel lifecycle during a rotation. It seems that generally ViewModel is preserved during a rotation. However this is not the case when I present ViewModels in MvxTabActivity. When the rotation happens it always calls a ViewModel constructor. </p>
  
  <p>I have used similar code structure as in N+1 tutorial <a href="https://github.com/slodge/NPlus1DaysOfMvvmCross/tree/master/N-25-Tabbed" rel="noreferrer">https://github.com/slodge/NPlus1DaysOfMvvmCross/tree/master/N-25-Tabbed</a>.</p>
  
  <p>Is there a way to modify this tutorial to keep ViewModels in memory during rotation when using MvxTabActivity?</p>