FILTERS: Various Chamberlin filter tuning

- optimized out a delay
- parameterization as described in Digital Sound Generation Part 2

Part of #14.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
FILTERS: Implement various improvements to the Chamberlin filter

This is part of #15.

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