Added Missing method & fixed potential issue with TreeSetBiIterators

src/builder/resources/speiger/assets/collections/templates/maps/impl/tree/AVLTreeMap.template

@@ -650,7 +650,7 @@ public class AVL_TREE_MAP KEY_VALUE_GENERIC_TYPE extends ABSTRACT_MAP KEY_VALUE_
 	}
 	
 	protected BI_ITERATOR KEY_GENERIC_TYPE keyIterator(KEY_TYPE element) {
-		return null;
+		return new AscendingKeyIterator(findNode(element));
 	}
 	
 	protected BI_ITERATOR KEY_GENERIC_TYPE descendingKeyIterator() {

src/builder/resources/speiger/assets/collections/templates/maps/impl/tree/RBTreeMap.template

@@ -650,7 +650,7 @@ public class RB_TREE_MAP KEY_VALUE_GENERIC_TYPE extends ABSTRACT_MAP KEY_VALUE_G
 	}
 	
 	protected BI_ITERATOR KEY_GENERIC_TYPE keyIterator(KEY_TYPE element) {
-		return null;
+		return new AscendingKeyIterator(findNode(element));
 	}
 	
 	protected BI_ITERATOR KEY_GENERIC_TYPE descendingKeyIterator() {