FILTERS: Add a prototype for Chamberlin filter

This is part of #11.
It does not include vectorization or any further improvement.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
FILTERS: Add the C++ implementation of the state variable filter

This is part of #11.
This is a very naive version (no vectorization).

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

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
TESTS: Add required header file for standard functional features

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
FILTERS: Add basic tests for Chamberlin filter

Fixes #13.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
SCRIPTS: Ignore compiled python files

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