Make creating AllAstNodeIter explicit.

This is to remove the ambiguity between calling iter on the specific structs like Document and calling iter on an AstNode by having an explicitly-named function to create the iterator.

src/iter/all_ast_node_iter.rs

@@ -90,12 +90,11 @@ impl<'r, 's> Iterator for AllAstNodeIter<'r, 's> {
     }
 }
 
-impl<'r, 's> IntoIterator for AstNode<'r, 's> {
-    type Item = AstNode<'r, 's>;
-
-    type IntoIter = AllAstNodeIter<'r, 's>;
-
-    fn into_iter(self) -> Self::IntoIter {
+impl<'r, 's> AstNode<'r, 's> {
+    /// Iterate all AST nodes.
+    ///
+    /// This is different from the iter/into_iter functions which iterate a single level of the children. This iterates the entire tree including returning the root node itself.
+    pub fn iter_all_ast_nodes(self) -> AllAstNodeIter<'r, 's> {
         AllAstNodeIter {
             root: Some(self),
             queue: VecDeque::new(),