Delete to trashcan needs to provide useful error messages

[stevenhl]

If a delete to trashcan fails, two thing must occur.

The error must be reported to the user in human-readable form (i.e. saymsg not Dos_Error). This is an expected error, not a should not occur error.

The code should offer to open the Trashcan so that the user can make space.

If not yet convinced that the code should offer to do the delete bypassing the Trashcan.