This example shows how to read and write plain ascii files, binary files and
hdf5 datasets.

For ascii files it shows how to obtain shogun's RealFeatures
(a simple feature matrix of doubles with 1 column == 1 example, nr_columns ==
 number of examples) and also sparse features in SVM light format.

Binary files use some custom native format and datasets can be read/written
from/to hdf5 files with arbitrary group / path.
