Free an object

        Entry:
          AH = 12h
          BH = 02h
          BL = object
               00h handle in DWORD on top of stack
                   Window: close window and free
                   Timer: free timer
                   Panel: free panel object
                   Pointer: free pointer
               01h task's window handle - kills task, never returns
               02h given task's mailbox (task's handle on top of stack)
               03h current task's mailbox
               04h given task's keyboard (task's handle on top of stack)
               05h current task's keyboard object