ocrad: new package

GNU Ocrad is an OCR (Optical Character Recognition) program
based on a feature extraction method.
It reads images in pbm (bitmap), pgm (greyscale) or ppm (color) formats
and produces text in byte (8-bit) or UTF-8 formats.

[Peter: fixup whitespace, install into STAGING_DIR, use make install, BR2_GNU_MIRROR]
Signed-off-by: Gilles Talis <gilles.talis@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>