fixed missing include for std::back_inserter.
fixed missing include for std::back_inserter.

with Visual Studio 2015 RTM:

Error C2039: 'back_inserter': is not a member of 'std'
Error C3861: 'back_inserter': identifier not found

need "iterator" with Visual Studio 2015 (vc14).

#include <iterator>
UB-Mannheim/tesseract,UB-Mannheim/tesseract,stweil/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,tesseract-ocr/tesseract,jbarlow83/tesseract,amitdo/tesseract,stweil/tesseract,jbarlow83/tesseract,jbarlow83/tesseract,amitdo/tesseract,amitdo/tesseract,amitdo/tesseract,tesseract-ocr/tesseract,amitdo/tesseract,jbarlow83/tesseract,UB-Mannheim/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,stweil/tesseract,jbarlow83/tesseract,stweil/tesseract,tesseract-ocr/tesseract,stweil/tesseract