ALGORITHMS: Now using a Hamming window for the spectrogram

This is as requested by the ASE descriptor, it may change later,
or required it to be parameterizable.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
ALGORITHMS: Add the ability to overlap popped data for the ringbuffer

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
ALGORITHMS: The spectrogram now uses overlapped pop from the ringbuffer

Part of #18.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
DESCRIPTORS: Add the AudioSpectrumCentroid

This is a very basic, unoptimized version.
Tests are currently not fulfilled.
Fixes #3.

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