Production issues

[AllenDowney]

phi gets rendered differently in different contexts.

For example, on page 31, phi looks different in an exponent or inline.

One option is to use exp() as a function everywhere, rather than e^{exponent}

[AllenDowney]

Exercises at the end of chapters are currently labeled Examples

[AllenDowney]

Figures containing a single graph are a little too big. The ones containing multiple graphs are too small.

[AllenDowney]

Figure placement needs tuning.

[AllenDowney]

Figures 11-2 and 11-5 exceed the bounds of the page.