Initialized on October 29, 2011.

10/29/11: initialize the package: v0.01.

10/30/11: merge the "spt" function with "chaosgame" function.  1)
remove plot=TRUE option; always draw the plot.  It can be saved to a
file manually. 2) initial point will not be specified by default.  By
default, randomly select a point within the plotting area. 3) adding
option chaosgame=FALSE to determine how to draw the SPT. 4) iteration
number will not be specified.  Taking default value 10000 for
"chaosgame" and 15 for regular drawing. 5) removing "main=NULL".  It
can be specified, but not prespecified. 6) "tol=0.00001" is removed,
and taken as default value.