avoid unnecessary cleanups of recovery files

* After the last commit 0b593eb7d0e6907b19cdbb605caf1becae351004
  we tried to clean up (unlink) recovery files for all dirty buffers.
  This resulted in superfluous file deletions before any recovery
  file was dumped; after disabling file recovery and even in
  batch mode.
  It's not tolerable that SciTECO scripts try to unlink files
  as a side effect e.g. of EW.
  Also, sometimes you may have to clean up recovery dumps even
  in batch mode, e.g. in Quit hooks.
* Also, it was broken for dirty unnamed buffers, which would
  cause glib errors.
* That's why we had to add another buffer state for
  dirty files with outdated recovery dumps (TECO_BUFFER_DIRTY_OUTDATED_DUMP).
  Once a dump was written, a buffer never directly transitions
  into the TECO_BUFFER_DIRTY_NO_DUMP state again.
  We can now reliably unlink() only where we'd expect a
  recovery file to exist in the first place.

0 files changed, 0 insertions, 0 deletions