2.3 - Bug fixing.

- CoreImage filters: use <code>[tesseract setRecognizeImageType:RecognizeImageTypeBlackAndWhite];</code> to convert the UIImage to recognize into a RecognizeImageType

- Rect: use <code>[tesseract setRect:CGRectMake(20, 20, 100, 100)]</code> to define the rect where the text must be recognized