Fixed multiple ticks/tildes inside code blocks

[fredck]

Fixes #300.

[martincizek]

I guess this should be applied only to the trailing newline:

code.replace(/^\n|\n$/g, '')

I've tested that if there is a newline after <pre><code>, then it is really rendered by the browser, i.e. it is a real part of the content and should appear as an empty line after the opening fence. It m

Correct me if I am wrong :)

[fredck]

@martincizek, you're totally right.

I've pushed the fix for it, including an additional test to be sure that we're preserving line breaks at the start/end of code blocks.

[domchristie]

Thanks for all this! Just a few minor suggestions. Let me know what you think.

[fredck]

Thanks for the suggestions, @domchristie. I've committed all of them.