TESTS: More removal of direct descirptor references

Part of #36.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
ALGORITHMS: Fix autocorrelation assert

The check was done on the bad window length.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
MANAGER: Move Spectrogram ringbuffer into the manager

Part of #37.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
ALGORITHMS: Remove useless header

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
TESTS: Temporary disable autocorrelation descriptor computation

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