Include from in subtree

Author: clarfonthey

lib/index.js

@@ -57,6 +57,12 @@ module.exports = (options = {}) => {
         }
 
         subtree = tree.parser(source);
+        subtree.options = subtree.options || {};
+        subtree.options.from = path.isAbsolute(src)
+            ? src
+            : tree.options.from
+              ? path.relative(tree.options.from, src)
+              : src;
         subtree.match = tree.match;
         subtree.parser = tree.parser;
         subtree.messages = tree.messages;