This is a complex demonstration of the PHP+HTML+JavaScript+CSS mixed-mode
    syntax highlight capabilities of CodeMirror.
    <?php ... ?> tags use the PHP parser, <script> tags use the JavaScript
    parser, and <style> tags use the CSS parser. The rest of the content is
    parsed using the XML parser in HTML mode.
    Features of the PHP parser:
    
      - special "deprecated" style for PHP4 keywords like 'var'
      
- support for PHP 5.3 keywords: 'namespace', 'use'
      
- 911 predefined constants, 1301 predefined functions, 105 predeclared classes
        from a typical PHP installation in a LAMP environment
      
- new feature: syntax error flagging, thus enabling strict parsing of:
        
          - function definitions with explicitly or implicitly typed arguments and default values
          
- modifiers (public, static etc.) applied to method and member definitions
          
- foreach(array_expression as $key [=> $value]) loops
        
 
- differentiation between single-quoted strings and double-quoted interpolating strings