Added make-city-edges

This function will create the city and will also place the 'cops' in
random locations
Added add-cops function

This function adds cops in a given alist...
Added edges-to-alist function

Right now I feel I'm the master copy-writer. These last two functions
are difficult to graps without having in mind the data we're dealing
with ...
At least I can tell it compiles. Need to see the basic pieces together
to get a better understanding of the data grrrr
Changing some names
added neighbors function

Given a node, this function search that node in the nested alist that is
passed as a parameter and obtains the list of neighbors nodes accessible
from the given node.

In this example I have executed the function and obtained this:

   CL-USER> (neighbors 3 '((3 (2 COPS) (1) (4)) (2 (3))))
   (2 1 4)
Added within-one, it will tell if b is between the neighbors of a

The function will return nil, if b is not a neighbor of a. But if b is
in that list, the complete list of neighbors will be returned.

   WITHIN-ONE
   CL-USER> (within-one 3 2 '((3 (2 COPS) (1) (4)) (2 (3))))
   (2 1 4)
   CL-USER> (within-one 3 2 '((3 (2 COPS) (1) (4)) (1 (3))))
   (2 1 4)
   CL-USER> (within-one 2 3 '((3 (2 COPS) (1) (4)) (2 (3))))
   (3)
   CL-USER> (within-one 2 1 '((3 (2 COPS) (1) (4)) (2 (3))))
   NIL
Added within-two function, which will tell if b is reachable in two steps

This function, will use within-one to determine if b is in the list of
neighbors of a. If not, the function will explore the neigborhs of the
neighbors and check if b is there.
Added make-city-nodes function ...

adds wumpus, glowworms, and the sound of the sirens (if there are cops
in the near edges).
defined new-game function, to initialize the game

This function will create the edges, nodes, with wumpus, cops, and
glowworms, and it will also get a position for the user.
It relies in the existence of the functions find-empty-node and
draw-city.
Added find-empty-nodes function

The function takes a random node, and checks it's cdr. If the cdr is not
empty, the function will try to find another node.
Added draw-city function
Some typos fixes
Fixed some more typos, now it works

After calling (new-game), it will generate a random map

   CL-USER> (new-game)
   T

And also the undirected graph in png in a city.png file