The template engine write a lot of blank lines where there is `_.each()` of `if`.
Instead of editing the template in a way to remove it, but reduce readability.
I prefer remove the blank lines here.

More details about the regex here: http://stackoverflow.com/a/16369725

`\s` is a special character class which is equivalent to `[ \f\n\r\t\v​\u00a0\u1680​\u180e\u2000​\u2001\u2002​\u2003\u2004​ \u2005\u2006​\u2007\u2008​\u2009\u200a​\u2028\u2029​​\u202f\u205f​ \u3000]` (it includes `\r`).
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/RegExp#character-classes

Moreover, Javascript regexes are greedy by default.
If a line ends with `\r\n`, the `\r` will match with `\s*` and the `\n` with `[\r\n]`.