Add a query method to answer whether or not the deck defines any wells.

opm/core/WellsManager.cpp

@@ -672,6 +672,12 @@ namespace Opm
     }
 
 
+    /// Does the "deck" define any wells?
+    bool WellsManager::empty() const
+    {
+        return (w_ == 0) || (w_->number_of_wells == 0);
+    }
+
 
 
     /// Access the managed Wells.

opm/core/WellsManager.hpp

@@ -53,7 +53,9 @@ namespace Opm
 
 	/// Destructor.
 	~WellsManager();
-        
+
+        /// Does the "deck" define any wells?
+        bool empty() const;
         
 	/// Access the managed Wells.
 	/// The method is named similarly to c_str() in std::string,