Drawing framed signal better in tests for sigproc.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Drawing tests better in features.py.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Improving tests and inserting the module 'useful'.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Correcting tests exhibition from module 'sigproc'.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Correcting tests exhibition from module 'features'.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Correcting tests exhibition from module 'corpus'.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>