增加一个link_buf类，以及log写入机制

hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/GraphTransaction.java

@@ -626,6 +626,7 @@ public class GraphTransaction extends IndexableTransaction {
              * unconcerned with add vertex
              */
             this.beforeWrite();
+            ////todo This is where the transaction feature needs to be added
             this.addedVertices.put(vertex.id(), vertex);
             this.afterWrite();
         } catch (Throwable e) {