Allow for hexadecimal encoding of delimiters where literal definition causes problems

I am often working with "mongrel files" that have some template markup, but content is in unrelated format. I want to have the templates as @file nodes with syntax highlighting, but with sentinels to be removed from generated file by templating engine. It is not practical to add language definition for every template+content combination, and @comment or @delim definitions cause syntax errors in their literal form, especially in XML formats.