770b4b363a
- `muscle` actuators take a new `tausmooth` attribute (defaults to 0) which when positive, smooths the transition between activation and deactivation timescales. - `mju_muscleDynamics` takes 3 parameters, adding width of smoothing sigmoid. PiperOrigin-RevId: 531473354 Change-Id: I8ab6c0289ff04437e798c3ca6edda132a30fcc31