node_t -> ast_node_t

Clearer to understand the intent of node_t as a direct result of
parsing source code.

parser.h

@@ -20,16 +20,16 @@ typedef struct
   size_t col, row;
   node_type_t type;
   int loop_ref;
-} node_t;
+} ast_node_t;
 
 struct PResult
 {
-  node_t *nodes;
+  ast_node_t *nodes;
   size_t size;
   size_t labels;
 };
 
-char *ast_to_str(node_t *ast, size_t size);
+char *ast_to_str(ast_node_t *ast, size_t size);
 struct PResult parse_buffer(buffer_t *buffer);
 
 #endif