Issue 2390 - when cloning DbCommand cloning the DesignTimeVisible property
can lead to deadlocks. So here allow providers to override how cloning a
DbCommand works and use this in SqlProviderServices to avoid the issue
that caused a deadlock.
Fix for EFTools in Visual Studio 14 CTP3: DpiHelperClass was moved to Microsoft.VisualStudio.Utilities for Dev14 so adding this reference conditionally. Also temporarily removing rule CA1809 from Code Analysis to be able to compile VirtualTreeControl with Dev14.