- Attempt to fix DVD writing by eliminating a number of the

  DVD subroutines to simplify.
- Modify DEVICE::open() to take dcr as first argument. This
  will permit providing more info to DVD opening.
- Fix scanning for time/size items which in some cases
  ate the next line.
- Eliminate read_dvd_volume_label().  New code (not yet written)
  *must* open dvd appropriately before calling
  read_dev_volume_label.
- Modify open_first_part() open_next_part() to take DCR as
  argument.
- Make label command from console work on DVDs.
- Make mount command from console work on DVDs.
  Unmount does not work yet.