Add different classes to hocr output depending on BlockType
Add different classes to hocr output depending on BlockType

These classes are taken from the hOCR specification, and seem
to map well onto the BlockType types. There are probably more that
could be added.

stweil/tesseract,amitdo/tesseract,tesseract-ocr/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,tesseract-ocr/tesseract,tesseract-ocr/tesseract,stweil/tesseract,tesseract-ocr/tesseract,amitdo/tesseract,UB-Mannheim/tesseract,stweil/tesseract,amitdo/tesseract,UB-Mannheim/tesseract,amitdo/tesseract,amitdo/tesseract,UB-Mannheim/tesseract,UB-Mannheim/tesseract,stweil/tesseract,stweil/tesseract