[ticket/13846] Fix softdelete feature workflow in viewtopic
Changes:
- For permanent deletion of softdeleted post, disapprove mode has been changed
to delete mode;
- If post delete and softdelete are allowed, delete button triggers softdelete
mode;
- If a user can't permanently delete posts but can restore softdeleted posts,
delete button won't be displayed for softdeleted posts.
Subsilver2 is unaffected.
