[Feature Request] Add variable resistance machines to equipment

[wsargent]

I use a vitruvian trainer which is essentially a cable machine that you stand on with two motors in it that provide variable resistance to the cables.

The Vitruvian app displays resistance as per cable, i.e. 100 lb per cable is 200 lbs total. There are some exercises that only use one cable, such as pull overs, but many exercises such as deadlifts and squats use both cables. There are no plates involved, and the Vitrivian can provide up to 0.5 lbs resolution although there is a floor of 8.8 lbs.

The equipment settings on Liftosaur do not account for variable resistance machines, and so the plate math calculations are not always accurate.

Instead, plate math for variable resistance machines should be divided by the number of cables used in the exercise and rounded to the machine resolution, taking the floor into account.