Add support for examples.

[abursavich]

Fixes #2

[abursavich]

Here's the output from a randomly selected package that has plenty of examples: README.md

It's worth noting that some of the output comments in their examples are intentionally malformed to appear in the Code section and not in the Output section, because the output contains source paths that may differ by environment and cause tests to fail. They appear the same here as they do in the godoc.

[hikhvar]

I would really like to see this merged. Are there any objections besides the conflicts?

[tmc]

@davecheney @abursavich -- Dave and Andy, would you be open to passing/taking the torch for this project so there's a spot for more active development? -- if you're open to it @abursavich perhaps @davecheney could modify the readme to point to your fork so folks can continue adding improvements there. Thoughts?