The CSS was causing the text bounding box to slightly overlap the
text. A kind person explained the problem by posting to issue 16.
However, his change didn't work. I removed the width field and for
some reason all the headings centered themselves. I tried changing
their alignment and that didn't work. I comprimised by changing 750
to 540 and that worked.
I also slightly changed the font size. It was almost comically large.
Moved the Q_DWPA function to filterpy.
Added help(x) calls for a couple of classes so the docstrings
are displayed in the book. This required me to change the
css style, because it was limiting output to a fairly
short height, and so the help was requiring scrolling.
