Wall()

         Simulates a wall

    Syntax:

         Wall( [nY1], [nX1], [nY1], [nX2], [cColor] ) -> Nil

         nY1    : Initial Y coordinate, default is 0
         nX1    : Initial X, default is 0
         nY2    : Final Y, default is 24
         nX2    : Final X, default is 79
         cColor : The color, optional

    Description:

         Draws a wall at the specified coordinates.

    Return:

         Nothing.

    Example:

         Wall( 1, 1, 20, 51, "W/G" )
         Wall( , , , , "GR/N" )