adding function findWellNode() to WellCollection

to return the WellNode* instead of WellGroupInterface*

opm/core/wells/WellCollection.cpp

@@ -116,6 +116,21 @@ namespace Opm
         return NULL;
     }
 
+
+    WellNode* WellCollection::findWellNode(const std::string& name) const
+    {
+        auto well_node = std::find_if(leaf_nodes_.begin(), leaf_nodes_.end(),
+                    [&] ( WellNode* w) {
+                    return w->name() == name;
+                    });
+
+        if (well_node != leaf_nodes_.end()) {
+            return *well_node;
+        } else {
+            return nullptr;
+        }
+    }
+
     /// Adds the child to the collection
     /// and appends it to parent's children.
     /// \param[in] child   the child node

opm/core/wells/WellCollection.hpp

@@ -95,6 +95,10 @@ namespace Opm
         /// \return the pointer to the group if found, NULL otherwise
         const WellsGroupInterface* findNode(const std::string& name) const;
 
+
+        WellNode* findWellNode(const std::string& name) const;
+
+
         /// Applies all group controls (injection and production)
         void applyGroupControls();