Fix system VesuvioFitting tests.

Converting the TOF from seconds to microseconds and then back seems
to have caused instability in the fitting when including the background.
It is actually more sensible to have convertToYSpace take the time in
seconds anyway.
Refs #8598

Code/Mantid/Framework/CurveFitting/src/ComptonPeakProfile.cpp

@@ -116,9 +116,9 @@ namespace CurveFitting
                                                "hwhm_lorentz");
     double yplus(0.0), yminus(0.0), dummy(0.0);
     detpar.efixed += dELorentz;
-    ConvertToYSpace::calculateY(yplus,dummy,dummy,m_mass,trec*1e6,k1,v1,detpar);
+    ConvertToYSpace::calculateY(yplus,dummy,dummy,m_mass,trec,k1,v1,detpar);
     detpar.efixed -= 2.0*dELorentz;
-    ConvertToYSpace::calculateY(yminus,dummy,dummy,m_mass,trec*1e6,k1,v1,detpar);
+    ConvertToYSpace::calculateY(yminus,dummy,dummy,m_mass,trec,k1,v1,detpar);
     // lorentzian width
     m_hwhmLorentz = 0.5*(yplus-yminus);
   }

Code/Mantid/Framework/CurveFitting/src/ComptonProfile.cpp

@@ -184,7 +184,7 @@ namespace CurveFitting
     {
       const double tsec = (isHistogram) ? 0.5*(tseconds[i] + tseconds[i+1]) : tseconds[i];
       ConvertToYSpace::calculateY(m_yspace[i], m_modQ[i],m_e0[i],
-                                  m_mass,tsec*1e06,k1,v1,detpar);
+                                  m_mass,tsec,k1,v1,detpar);
     }
   }
 

Code/Mantid/Framework/CurveFitting/src/ConvertToYSpace.cpp

@@ -141,17 +141,16 @@ namespace CurveFitting
    * @param qspace Output qspace value
    * @param ei Output incident energy value
    * @param mass Mass value for the transformation
-   * @param tmicro Time-of-flight in microseconds
+   * @param tsec Time-of-flight in seconds
    * @param k1 Modulus of wavevector for final energy (sqrt(efixed/massToMeV)), avoids repeated calculation
    * @param v1 Velocity of neutron for final energy (sqrt(efixed/massToMeV)), avoids repeated calculation
    * @param detpar Struct defining Detector parameters @see ComptonProfile
    */
   void ConvertToYSpace::calculateY(double & yspace, double & qspace, double &ei,
-                                   const double mass, const double tmicro,
+                                   const double mass, const double tsec,
                                    const double k1, const double v1,
                                    const DetectorParams & detpar)
   {
-    const double tsec = tmicro*1e-06;
     const double v0 = detpar.l1/(tsec - detpar.t0 - (detpar.l2/v1));
     ei = MASS_TO_MEV*v0*v0;
     const double w = ei - detpar.efixed;
@@ -254,7 +253,7 @@ namespace CurveFitting
     for(size_t j = 0; j < npts; ++j)
     {
       double ys(0.0),qs(0.0),ei(0.0);
-      calculateY(ys,qs,ei,m_mass,inX[j],k1,v1,detPar);
+      calculateY(ys,qs,ei,m_mass,inX[j]*1e-06,k1,v1,detPar);
       const size_t outIndex = (npts - j - 1);
       outX[outIndex] = ys;
       const double prefactor = qs/pow(ei,0.1);