Updated pywidgets version to 4.2 to allow the notebooks to run.
Put import __future__ as the first line in each file to avoid
error stating that it must be the first line. Not sure when this
changed, it worked before.
Not sure why, but the two line title was being cut off when
displayed. I must have changed somethign in the matplotlib
sytle at some point that broke this.
I plan to reorder the design so that the prediction is
fully implemented and I show an example. The chapter just goes
on and on with no examples. Plus, talking about Q just after
discussion Fx makes the most sense.
