SVK::Editor::TxnCleanup - An editor that aborts a txn when it is aborted

 my $editor = ...
 # stack the txn cleanup editor on
 $editor = SVK::Editor::TxnCleanup-> (_editor => [$editor], txn => $txn );
 # ... do some stuff ...
 $editor->abort_edit;
 # $txn->abort gets called.