Suggestion: Show block folding, and/or tabs/spaces

[neeklamy]

It would be a lot easier to follow the longer code blocks if block folding were illustrated somehow.

I had a slight issue with the reference code for spec/controllers/book_controller_spec.rb, with it spanning three pages, and with the multiple edits required, I deleted an end and took some time to find where it was missing.

Line numbers would be nice too, something like this:

If not block folding, how about showing tabs or spaces:

[jasonswett]

Also a good idea. In future versions I should probably include the Git repo of not just the code that comes with the book but the markdown for the book as well. I'm still trying to figure out a good format.