Program 5	Dordal		Due: April 16, 2004

Last-minute fix: StoneRoom::on_entry() was mistakenly called onentry(), 
which meant that it did not get invoked. 

You are to modify the game program presented in class, adding the
following features:

1. Add a second Lantern, of class Lantern. The second Lantern can
have the same name, LANTERN, or a new name, FLASHLIGHT. Try to implement
this in such a way that when the user invokes the command
	LIGHT FLASHLIGHT 	(or LIGHT LANTERN)
for the second Lantern, you look on the Inventory for the named 
object and light() it. Note that you will need to downcast
from Carryable* to Lantern* to do this. 
Similarly, in the dark rooms, you will need to check whether
either Lantern is on Inventory. An even better approach is to
see if there is anything on Inventory that is of type Lantern.


2. If you eat the chocolate, it should go away.

Optional: the chocolate should last 2-3 bites. Keep the number of bites left
as an attribute of the chocolate itself. 


3. Introduce a puzzle room where you cannot *leave* the room until some
action occurs. Possibilities are:
    You have to FIGHT the dragon (with a SWORD?)
    You have to GIVE the dragon a PRESENT or COOKIE.
    There is a cave-in and you have to DIG (with SHOVEL?)


4. Introduce a class DarkRoom (intended to apply to the cave area,
but possibly to the Hollow Tree as well). In a DarkRoom, the following
rules apply:
	1. You cannot go from one DarkRoom to another without a light.
	2. On entry to a DarkRoom, if you don't have a light you are
	   warned to get one!
	3. If you don't *leave* the DarkRoom by the second turn,
	   a "grue" will get you and you die. DarkRoom should keep
	   a counter of the number of times DarkRoom::response()
	   is called, reset to 0 by DarkRoom::onentry(). 
	4. If you do have a light with you, DarkRoom behaves exactly
	   the same as Room.
	5. Note that it is possible to DROP the light, in which case
	   the Dark rules again should be in force.
Make all cave passages DarkRooms. (You may need to add some extra 
cave.) Note that this involves changing the parent structure: the
existing StoneRoom will now have DarkRoom rather than Room as a parent.
Note also that DarkRoom may have its behavior overridden by, say,
StoneRoom; this is probably not a serious difficulty in practice.


5. You are to add one additional puzzle of your own. Your puzzle should,
at a minimum, involve the following:
	one new CarryObj 
	one new verb 
	one new derived room class, with special behavior for 
		at least one verb (new or existing).
	some kind of state change to the room or to an object
	 	(like the stone being moved or valve being turned)
You will be graded in part on the inventiveness of your puzzle.

Here are a few possibilities.

UNLOCK CHEST with a KEY found elsewhere; once the chest is unlocked,
something should be inside.

Cross a rickety two-move bridge over a bottomless pit; if you carry too
much the bridge will break; you can only carry two things at a time.

You need to CAST SPELL in the WizardsChamber, but in order to do this
you must first find in the game a BELL, BOOK, and CANDLE. (And maybe
LIGHT CANDLE? Or maybe, in the simpler direction, just find NEWTEYE 
and BATWING. If you try to CAST SPELL and don't have the ingredients,
the game should tell you what you're missing.)


Be sure all verbs you introduce are handled at some primitive level
by Room::response(), so that they're not completely unrecognized
even if you're not in the "right" room.