Redesign Muscle to exploit MCI and improve robustness

[tkuchida]

• Add MuscleActivationDynamics as a subcomponent of Muscle.
• Eliminate the duplicate MuscleFirstOrderActivationDynamicModel (replaced by FirstOrderMuscleActivationDynamics).
• Rename ZerothOrderMuscleActivationDynamics to NoMuscleActivationDynamics.
• Remove pennation angle property from Muscle.
• Make MuscleFixedWidthPennationModel a property and subcomponent of Millard2012{Equilibrium|Acceleration}Muscle --or-- create pennation model classes mirroring the new activation dynamics classes and make a property of Muscle.
• Avoid inconsistencies in fiber length by removing calls to MuscleFixedWidthPennationModel::clampFiberLength() from muscle models.
• Add tests for each component in isolation and also ensure they function correctly once hooked into a Muscle.
• …

[aseth1]

I like where this is going. Why not go straight to Muscle including the slots for its submodels (e.g. its concrete MuscleActivationDynamics?). Otherwise we are going to duplicate for Millard, etc... Also a secondary point, I don't think people are going to figure out what ZerothOrderMuscleActivationDynamics means. NoActivationDynamics or something along those lines may be clearer?

[tkuchida]

Why not go straight to Muscle including the slots for its submodels (e.g. its concrete MuscleActivationDynamics?).

Sounds like a good plan, though that will be a big job since it will affect all muscles.

NoActivationDynamics or something along those lines may be clearer?

I propose NoMuscleActivationDynamics so we have {NULL|No|FirstOrder}MuscleActivationDynamics classes.

[aseth1]

The unspecified case would default to NoMuscleActivationDynamics, so there wouldn't be a NULL MuscleActivationDynamics model case.

[aseth1]

Also

I propose NoMuscleActivationDynamics

👍

[tkuchida]

The unspecified case would default to NoMuscleActivationDynamics, so there wouldn't be a NULL MuscleActivationDynamics model case.

I meant that the abstract class would be named MuscleActivationDynamics and all concrete classes would be named SOMETHINGMuscleActivationDynamics.