Minor updates to chapter 5, typesetting in 3.

Some changes to chapter 5 to improve readability and cure minor typesetting glitches (and similarly in chapter 3).  Added text at the end of chapter 5 to explain the example (list sum with funs) a bit.
Minor typesetting changes for chapter 6.
Merge pull request #10 from nuked/master

Various updates for typesetting.