Update Rouge to 3.x

[TWiStErRob]

Rouge version 3.x has been released for over a year now, is there any reason for not updating to it?

https://github.com/jneen/rouge/blob/master/CHANGELOG.md#version-300-20170921

[Krinkle]

There've also been a number of bugs fixed in 3.x that were previously causing error-colors to be used for valid syntax, such as "\n" in a string in JavaScript. Would recommend at least 3.2.0 or higher.

https://github.com/jneen/rouge/blob/v3.2.0/CHANGELOG.md