Add class to code

[ryanapil]

``` {.hljs .css}
div.code {
    selector: value;
} ```

this doesn't return as expect, using the demo the php markdown extra works as intended but the parsedown just displays the {} as content

[Taufik Nurrohman]

My ParsedownExtraPlugin extension has this feature. Check the test file: https://github.com/tovic/parsedown-extra-plugin/blob/master/test/test.blockCodeAttributes.php

[ryanapil]

@tovic thanks now works a treat! https://blog.ryanapil.uk/article/3/client-side-customisation