pwSetFitLimitsAroundCurrentValues

 pwSetFitLimitsAroundCurrentValues(factor)

 Sets the limits of the currently fitted parameters k, x0, and s
 around the current values.

 factor:  If 10 (default), the fit limits will be [par/10 par*10]
          In general:
          lower limit: par / factor
          upper limit: par * factor

 Temp. fixed parameters are untouched.