* `Dummy` trait
* More generic design for `Arith`
* Distinguish between incoming and running instances in ProtoGalaxy
* Format
* Fix unit test
* Fix incorrect arguments supplied to `CycleFoldWitness::dummy`
* `RUNNING` and `INCOMING` constants
* Better name and docs for `eval_core`
* More docs for `Arith` methods and implementations
* Fix missing imports