- Update Syntax Highlighter to version 4.

- Build Syntax Highlighter based on https://github.com/syntaxhighlighter/syntaxhighlighter/wiki/Building and use theme generated by fxn.
- This also bundles these brushes in the file itself- ruby,css,xml,sql,javascript,plain. Generation command used:
gulp build --compat --brushes=javascript,ruby,xml,sql,plain --theme=/Path/To/RailsSource/rails/guides/assets/stylesheets/syntaxhighlighter/shThemeRailsGuides.css
- rm all old js and css files
- Moved over how JS configuration is created for Syntax Highlighter
- Fixed layout for all imports
- Fixes bug with old copy paste, generating wrong space character on webkit https://github.com/syntaxhighlighter/syntaxhighlighter/blob/7caa9632e7fe470d944fc06b4db7d35352ebaa36/src/dom.js#L227

 Fixes rails#25655

Author: vipulnsward

guides/assets/javascripts/guides.js

@@ -51,9 +51,3 @@ var guidesIndex = {
     window.location = url;
   }
 };
-
-// Disable autolink inside example code blocks of guides.
-$(document).ready(function() {
-  SyntaxHighlighter.defaults['auto-links'] = false;
-  SyntaxHighlighter.all();
-});