kes Put attach_dcr_to_dev in a subroutine.

kes  Put attach_dcr_to_dev in a subroutine.
kes  Make attaching/detaching to/from a device use a flag and
     only detach if actually attached.
kes  Add dvd-simulator.in to scripts directory and add to configure.
kes  Fix code in acquire.c that checks fd != 0 to use dev->is_open().
     This could be a cause of a number of drive reservation problems.
     Note, this code is now in attach_dcr_to_dev().
kes  Suppress doing Volume updates if it is a system job.  This should
     prevent the DVD label blocking.
kes  Clear the freespace ok flag in a couple of strategic places.