List available languages recursively
List available languages recursively

Tesseract supports hierarchies of languages and uses them since
the new files best/*.traineddata were added.

Now `tesseract --list-langs` also shows any traineddata files in
subdirectories of the tessdata directory.

Signed-off-by: Stefan Weil <8d4c780fcfdc41841e5070f4c43da8958ba6aec0@weilnetz.de>

UB-Mannheim/tesseract,stweil/tesseract,stweil/tesseract,amitdo/tesseract,jbarlow83/tesseract,stweil/tesseract,tesseract-ocr/tesseract,jbarlow83/tesseract,amitdo/tesseract,amitdo/tesseract,UB-Mannheim/tesseract,stweil/tesseract,jbarlow83/tesseract,amitdo/tesseract,jbarlow83/tesseract,tesseract-ocr/tesseract,jbarlow83/tesseract,amitdo/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,UB-Mannheim/tesseract,stweil/tesseract,UB-Mannheim/tesseract,tesseract-ocr/tesseract,tesseract-ocr/tesseract