permissives do not appear in sediff

[jbrindle]

old sediff diffed permissive domains, this one does not.

[pebenito]

It does, but it displays it as a modified type:

$ ./sediff -t tests/diff_left.conf tests/diff_right.conf       
Types (1 Added, 1 Removed, 6 Modified)
   Added Types: 1
      + added_type
   Removed Types: 1
      - removed_type
   Modified Types: 6
      * modified_add_alias (1 Added aliases)
          Aliases:
          + an_alias
      * modified_add_attr (1 Added attributes)
          Attributes:
          + an_attr
      * modified_add_permissive (Added permissive)
      * modified_remove_alias (1 Removed aliases)
          Aliases:
          - an_alias
      * modified_remove_attr (1 Removed attributes)
          Attributes:
          - an_attr
      * modified_remove_permissive (Removed permissive)