Revision 38810

  Patch to correctly honour selector abort status settings in PROOF. Currently only
  the TSelector::kAbortProcess was handled by stopping processing. In particular
  TSelector::kAbortFile was ignored; this recently created some problems in ALICE
  with corrupted files, with repeated attempts to read events eventually leading to
  bad_alloc exceptions.

  This patch also fixes other related issues, in particular with the reporting of the
  non-processed {files, events} in the final 'MissingFiles' list. This list should
  now account much more precisely of the number of events which could not be processed.

  It also fixes a problem with the final update of the progress information affecting
  occasionally cases with skipped events.