Extend syntax for the native fenced code block.

Feature:

• Extend syntax for the native fenced code block.
• Use tag-plugins as fenced code block.

```javascript var foo = "bar"; ``` 

```javascript+ var foo = "bar"; ``` 

or

````javascript var foo = "bar"; ```` 

The code will be inserted as a script block:

<script> var foo = "bar"; </script>

```javascript- var foo = "bar"; ``` 

or

`````javascript var foo = "bar"; ````` 

Note: Only JavaScript, CSS and HTML code can be inserted into a post. This feature is handily for building a quick demo.

The native tag plugin looks like this:

• block

  {% tagname [option1] [option2] ... %} content {% endblockquote %}

• inline

  {% tagname [option1] [option2] ... %}

Use the syntax sugar as follow:

• block

   ```tagname [option1] [option2] ... content ``` 

• inline

   ```tagname [option1] [option2] ... ``` 

• hexo-toc Insert a markdown TOC before posts be rendered.
• hexo-filter-flowchart Generate flowchart diagrams for Hexo.
• hexo-filter-sequence Generate UML sequence diagrams for Hexo.
• hexo-filter-sub Generate subscript (<sub>) tag for Hexo.
• hexo-filter-sup Generate superscript (<sup>) tag for Hexo.
• hexo-theme-formula Hexo theme base on jade and less.

Pull requests and stars are highly welcome.

For bugs and feature requests, please create an issue.