class AliTPCExBEffectiveSector: public AliTPCCorrection

AliTPCExBEffectiveSector class
 Correct for the rest of ExB effect which are not covered yet by physical models

 Motivation:
   ExB correction:
      dr    =  c0* integral(Er/Ez) + c1* integral(Erphi/Ez)
      drphi = -c1* integral(Er/Ez) + c0* integral(Erphi/Ez)
   Where:
   wt = Bz*(k*vdrift/E)           ~ 0.3 at B=0.5 T
   c0 = 1/(1+T2*T2*wt*wt)
   c1 = T1*wt/(1+T1*T1*wt*wt)


  3 correction maps 0 implemented as histogram used
  R-Phi correction map obtained minimizing residuals betwee the track
        and space points (AliTPCcalibAlign class). Track is defined using
        the points from the refernce plain at the middle of the TPC
        and vertex
        Corrected primar tracks straight pointing to the primary vertex

  R distortion - obtained using the cluster residuals in the setup with
                 plus and minus field
                 Only high momenta tracks used for this calibration (1 GeV threshold)
     drphi_plus-drphi_minus=-2*c1 integral(Er/Ez)
               - Erphi/Ez cancels