Stimulus smoothing
------------------

*  **stim_phtau** - phosphor decay time constant (s) for CRT emulation,
     default value is 0.006.  Currently implemented for the following stimuli:

  * sine
  * sine_seq
  * ransinphase, ransinori, ransindir


*  **stim_smooth** - (deg, 0.0 default - none) SD for Gaussian
   smoothing, **beware wrap-around**.


*  **stim_smooth_t** - (s, 0.0 default - none) peak of Maxwell
   function (sec), **beware wrap-around**.