original/limited bar graph

A bit of a pain to get the R settings in, but it works now.

One nice thing to add would be to make the bar graph relative
frequency instead of straight count -- both the scale and the comparative
graph would be much more useful.
switch to using relative frequency

(as described in previous commit)
make it a little easier to see the line on bar graph

change bars to blue, and alpha to 0.75 so you can see the line
through them
bugfix: data not being restored properly

It was actually more complicated than that, because the problem was
that in a number of places I tested for whether there were limits
with "if origData". In fact, the data was being restored just fine
by restoreData(), but restoreData wasn't setting origData back to
null. However, the best way to fix it turned out to be to change
the conditional to "if origData != data", because a number of other
places save to origData before potentially doing nothing, and
changing that would be both more effort and more fragile than
changing the condition, and the new one is more accurate anyway.