Fix Bug 1102508: Link syntaxboxes to Syntax Help Article

Added javascript to detect syntaxbox and twopartsyntaxbox and create a link to help articles based on if there is a CSS class identifying the language, falling back to the language the section is in if there is not.

Prevented prism from styling syntaxbox and twopartysyntaxbox so that we can link the syntax to articles explaining it.

Added CSS to support new help link and to style the syntaxboxes without the help of prism.
Is `.sxyntaxbox-help` the icon referred to? If so, we could move `margin-left` below `width` and do:

```
margin-left: -@width;