indented markdown loses linebreaks

![linebreaks](https://cloud.githubusercontent.com/assets/70221/2540283/5f2aa08c-b5d1-11e3-99d2-2f6aaafe075b.png)

An indentation of 4 or more spaces in markdown results in `<pre><code>` around the lines, and is expected to be used for things like inline source code examples and as such should preserve linebreaks.