Modify file attributes without using octets

[roberthawdon]

The documentation for NET-DFEDIT has the following when talking about modifying file attributes on Unix:

      3.7.8.2 MODIFYING XENIX FILE ATTRIBUTES

     If the file is a Xenix file (from the server) the prompts are:

          Modify file attributes ([ugo] +|-|= rwx):
          Modify multiple file attributes ([ugo] +|-|= rwx):

     This command uses the same syntax as the Xenix chmod command. Who
     is  specified by "u" for user (owner), "g" for group, and "o" for
     other. Who can be any combination of these in any order or  blank
     for  just  all three. The "+" means add the permission, "-" means
     remove the permission, and "=" means only  set  this  permission.
     The  permissions  are  "r" for read access, "w" for write access,
     and "x" for execute or search access.

This should be implemented in DF-SHOW as an alternative to using the octet input.

[roberthawdon]

Moved to v0.10.0 milestone