Add dependency messages for nested includes

Author: devongovett

lib/index.js

@@ -45,6 +45,7 @@ module.exports = (options = {}) => {
         subtree = tree.parser(source);
         subtree.match = tree.match;
         subtree.parser = tree.parser;
+        subtree.messages = tree.messages;
         content = source.includes('include') ? posthtmlInclude(subtree) : subtree;
 
         if (tree.messages) {