Exposure of Solve for equilibrium for actuator states should be minimized

[aseth1]

##Feature Request

In the majority of cases Solve for equilibrium for actuator states is the correct default condition and if not selected results in slow and incorrect simulations, which can be jarring for users.

The option is required when the user has predefined state(s) they prefer to use instead of the equilibrated values for muscles.

It would be simpler for users if the check box only appeared or was only enabled if a states file is provided. This would require no API change.

The option could also be eliminated if we informed users that muscle will be equilibrated if muscle states are not provided in a states file. This would require minor changes to the Tools.

[aseth1]

From user testing session:

{Feature Request} Remove "Solve for equilibrium for actuator states" box and just make that behavior is true for everything

[gattia]

Bumping this thread as I just had a blow-up in Joint Reaction Analysis because I didn't check the box.