* Finally tracked down the WC->vars heap corruption issue (for real this

* Finally tracked down the WC->vars heap corruption issue (for real this
  time).  We now call clear_local_substs() at the end of each HTTP
  transaction, whether we need to or not, instead of calling it whenever
  we're done with something we wanted session variables for.
* Finally tracked down the years-long "misplaced '(edit)' link" bug, by
  copying serv_info->serv_pid to WC->ctdl_pid at the time it's loaded,
  preventing it from getting clobbered by another session.
* Bumped internal version number to 5.27