Updating doc.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Improving test in features/sigproc.py

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Transposing the mfcc() output. Now, rows are features and columns, frames.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
New delta() function for mfcc transposed.

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