Use onPageContentRaw instead of onPageContentProcessed hook

[manuszep]

Use onPageContentRaw instead of onPageContentProcessed hook to avoid getting the shortcode output wrapped in a paragraph tag.

In the current version, when you use the [center]text[/center] block shortcode, the output is

<p><div style="text-align: center;">text</div></p>

To avoid that extra p tag, I used the onPageContentRaw hook which will inject markup before markdown is processed.

[manuszep]

It's worth mentionning that the markdown extra option should be activated and the markdown="1" attribute needs to be added on the wrapper element. ex:

<div style="text-align: center;" markdown="1">text</div>

Otherwise, the markdown inside the HTML tags is not processed.

[rhukster]

This actually breaks LOTs of stuff. markdown is no longer processed when encapsulated in HTML, so have it firing first effectively means you will no longer be able to use markdown inside shortcode. That's simply not an acceptable compromise.