FILTERS: Generic management of filter delays

Fixes #22

Signed-off-by: G4m4 <misept.dieseneuf@gmail.com>
TESTS/FILTERS: Using the new generic delay meta parameter

Part of #22.

Signed-off-by: G4m4 <misept.dieseneuf@gmail.com>
FILTERS: Add an improved version of the Chamberlin SVF

Implements #15.

Signed-off-by: G4m4 <misept.dieseneuf@gmail.com>