Fixed a minor bug in extract_highdim_face_lbp_descriptors() which was pointed

out by Yan Xu.  One of the face locations was mistakenly used twice while
another was skipped.  This change breaks backwards compatibility with the
previous feature extraction output but should slightly improve accuracy of
classifiers trained using these features.

dlib/image_transforms/lbp.h

@@ -248,7 +248,7 @@ namespace dlib
         parts.push_back(det.part(17));
         parts.push_back(det.part(21));
         parts.push_back(det.part(22));
-        parts.push_back(det.part(28));
+        parts.push_back(det.part(26));
         parts.push_back(det.part(36));
         parts.push_back(det.part(39));
         parts.push_back(det.part(42));