Added Backport for PropertyInfo.GetValue
Added  Backport for PropertyInfo.SetValue
Fixed warning in NET 4.0 y 4.5

NewOperationCancelledException will have no code in .NET 4.0 and .NET
4.5 because there OperationCancelledException already has the
CancellationToken.
Added missing constructors
WhereMatch renamed to Where

WhereMatch should blend with Where from Linq
Clean up
Better conditional compilation

There should be no ambiguities introduced in existing code by adding
these libraries for the right .NET version.