Change parameter names of frequency sweep sources from fMin and fMax to fStart and fStop

[christiankral]

In #2452 the frequency sweep behavior has been changed, such that the following cases are now allowed in model Modelica.ComplexBlocks.Sources.LogFrequencySweep:

• wMin < wMax
• wMin == wMax
• wMin > wMax

As a consequence of this change, it makes sense to rename the parameters of the newly models, since this is NO backwards compatibility issue:

• Modelica.Electrical.QuasiStationary.SinglePhase.Sources.FrequencySweepVoltageSource
• Modelica.Electrical.QuasiStationary.SinglePhase.Sources.FrequencySweepCurrentSource
• Modelica.Electrical.QuasiStationary.MultiPhase.Sources.FrequencySweepVoltageSource
• Modelica.Electrical.QuasiStationary.MultiPhase.Sources.FrequencySweepCurrentSource

Change from

  parameter Modelica.SIunits.Frequency fMin(start=1) "Lower sweep frequency";
  parameter Modelica.SIunits.Frequency fMax(start=1) "Upper sweep frequency";

to

  parameter Modelica.SIunits.Frequency fStart(final min=eps, start=1) "Start sweep frequency";
  parameter Modelica.SIunits.Frequency fStop(final min=eps, start=1) "Stop sweep frequency";