General grammar and style fixes in the book

Contains numerous grammar, style and readability fixes (see diff)

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | >= 2.3
| Fixed tickets | 
http://www.quickanddirtytips.com/education/grammar/ie-versus-eg

In this context it should probably be ```e.g.```