ALGORITHMS: Move Pi definition into the common algorithms definitions

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
ALGORITHMS: Add a windowing object

Fixes #22, although this is still a very basic version.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
ALGORITHMS: Use the new apodizer object in the spectrogram

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
SCRIPTS: Fix missing license

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
SCRIPTS: Add a script sandbox for window functions generation

Signed-off-by: Gama <misept.dieseneuf@gmail.com>