PCL changes according to http://blog.xamarin.com/how-to-update-nuget-packages-for-64-bit/
Fixes for StringSize and DrawString changes in Xamarin iOS
Merge remote-tracking branch 'upstream/3.5' into 3.5

Conflicts:
	CrossUI/CrossUI.Touch/Dialog/Elements/DateTimeElement.cs
	CrossUI/CrossUI.Touch/Dialog/Elements/MessageSummaryView.cs