add operator for issue #860

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

src/api/dotnet/Solver.cs

@@ -18,6 +18,7 @@ Notes:
 --*/
 
 using System;
+using System.Linq;
 using System.Collections.Generic;
 using System.Diagnostics.Contracts;
 
@@ -126,6 +127,14 @@ namespace Microsoft.Z3
             Assert(constraints);
         }
 
+        /// <summary>
+        /// Alias for Assert.
+        /// </summary>        
+        public void Add(IEnumerable<BoolExpr> constraints)
+        {
+            Assert(constraints.ToArray());
+        }
+
         /// <summary>
         /// Assert multiple constraints into the solver, and track them (in the unsat) core 
         /// using the Boolean constants in ps.