Function set_hidden_exits:
Defined in module m_exit (file: /std/modules/m_exit.c)

This is the list of exits to NOT be shown to the mortals in the room.
If "all" is any of the arguements in exits_list all exits for the object 
will be marked as hidden regardless to the rest of the arguments.

Prototype:
void set_hidden_exits( string array exits_list ... );
