AVLTreeMap/TwoKeyAVLTree: More access to nodes

both:
* Add Previous()/Next().
* Add Insert() version that returns a Node* instead of an Iterator.
* Add Remove() version that takes a Node* instead of a key.

TwoKeyAVLTree:
* Add GetIterator() version that takes an additional Node*, i.e.
  initializing an iterator to point to the node.
* Add Iterator::CurrentNode().

headers/private/kernel/util/AVLTreeMap.h

@@ -65,6 +65,9 @@ public:
 
 			Node*				RootNode() const;
 
+			Node*				Previous(Node* node) const;
+			Node*				Next(Node* node) const;
+
 	inline	Iterator			GetIterator();
 	inline	ConstIterator		GetIterator() const;
 
@@ -76,7 +79,10 @@ public:
 
 			status_t			Insert(const Key& key, const Value& value,
 									Iterator* iterator);
+			status_t			Insert(const Key& key, const Value& value,
+									Node** _node = NULL);
 			status_t			Remove(const Key& key);
+			status_t			Remove(Node* node);
 
 			const NodeStrategy&	GetNodeStrategy() const	{ return fStrategy; }
 
@@ -185,6 +191,13 @@ public:
 		return NULL;
 	}
 
+	inline Node* CurrentNode()
+	{
+		if (AVLTreeNode* node = fTreeIterator.Current())
+			return fParent->_GetNode(node);
+		return NULL;
+	}
+
 	inline bool HasNext() const
 	{
 		return fTreeIterator.HasNext();
@@ -270,6 +283,32 @@ _AVL_TREE_MAP_CLASS_NAME::RootNode() const
 }
 
 
+// Previous
+_AVL_TREE_MAP_TEMPLATE_LIST
+inline typename _AVL_TREE_MAP_CLASS_NAME::Node*
+_AVL_TREE_MAP_CLASS_NAME::Previous(Node* node) const
+{
+	if (node == NULL)
+		return NULL;
+
+	AVLTreeNode* treeNode = fTree.Previous(_GetAVLTreeNode(node));
+	return treeNode != NULL ? _GetNode(treeNode) : NULL;
+}
+
+
+// Next
+_AVL_TREE_MAP_TEMPLATE_LIST
+inline typename _AVL_TREE_MAP_CLASS_NAME::Node*
+_AVL_TREE_MAP_CLASS_NAME::Next(Node* node) const
+{
+	if (node == NULL)
+		return NULL;
+
+	AVLTreeNode* treeNode = fTree.Next(_GetAVLTreeNode(node));
+	return treeNode != NULL ? _GetNode(treeNode) : NULL;
+}
+
+
 // GetIterator
 _AVL_TREE_MAP_TEMPLATE_LIST
 inline typename _AVL_TREE_MAP_CLASS_NAME::Iterator
@@ -354,6 +393,32 @@ _AVL_TREE_MAP_CLASS_NAME::Insert(const Key& key, const Value& value,
 }
 
 
+// Insert
+_AVL_TREE_MAP_TEMPLATE_LIST
+status_t
+_AVL_TREE_MAP_CLASS_NAME::Insert(const Key& key, const Value& value,
+	Node** _node)
+{
+	// allocate a node
+	Node* userNode = _Allocate(key, value);
+	if (!userNode)
+		return B_NO_MEMORY;
+
+	// insert node
+	AVLTreeNode* node = _GetAVLTreeNode(userNode);
+	status_t error = fTree.Insert(node);
+	if (error != B_OK) {
+		_Free(userNode);
+		return error;
+	}
+
+	if (_node != NULL)
+		*_node = userNode;
+
+	return B_OK;
+}
+
+
 // Remove
 _AVL_TREE_MAP_TEMPLATE_LIST
 status_t
@@ -368,6 +433,19 @@ _AVL_TREE_MAP_CLASS_NAME::Remove(const Key& key)
 }
 
 
+// Remove
+_AVL_TREE_MAP_TEMPLATE_LIST
+status_t
+_AVL_TREE_MAP_CLASS_NAME::Remove(Node* node)
+{
+	if (!fTree.Remove(node))
+		return B_ENTRY_NOT_FOUND;
+
+	_Free(node);
+	return B_OK;
+}
+
+
 // CompareKeyNode
 _AVL_TREE_MAP_TEMPLATE_LIST
 int