merge unstable into opt

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/api/dotnet/Context.cs

@@ -3565,7 +3565,7 @@ namespace Microsoft.Z3
         /// </summary>
         /// <remarks>
         /// The list of all configuration parameters can be obtained using the Z3 executable:
-        /// <c>z3.exe -ini?</c>
+        /// <c>z3.exe -p</c>
         /// Only a few configuration parameters are mutable once the context is created.
         /// An exception is thrown when trying to modify an immutable parameter.
         /// </remarks>
@@ -3691,7 +3691,7 @@ namespace Microsoft.Z3
         internal Optimize.DecRefQueue Optimize_DRQ { get { Contract.Ensures(Contract.Result<Optimize.DecRefQueue>() != null); return m_Optimize_DRQ; } }
 
 
-        internal uint refCount = 0;
+        internal long refCount = 0;
 
         /// <summary>
         /// Finalizer.