No good way to display code blocks

[ericvicenti]

Its very difficult to display the code blocks properly here:

http://markshow.org/Specification#code

Nesting code blocks does not work, which is probably what we want..

Also, there is some issue when using backslash escapes like ``` in code blocks.

edit: wow.. this is a hard issue to talk about with github flavored markdown in the mix here