Include some additional aliases for JS, XML and Cpp

This pull request includes support for:
  aliases: 'cc', 'c++', 'c', 'h', 'hpp', 'h++' in the Cpp brush type
  aliases: 'json' in the JScript brush type
  aliases: 'plist' in the Xml brush type

It also supports tags starting with <! to allow for doctype tags to be highlighted in the Xml brush type.