Remove separate tool for Bethe Heitler energy loss effects, merge code as part of CombinedMaterialEffects

Merge the code for Bethe Heitler energy loss effects (brem) to be part of the CombinedMaterialEffects.

After the recent cleanup it is probably easier to have all material effects in one place. Also allows for the removal of some not really used code...

Tracking/TrkFitter/TrkGaussianSumFilter/TrkGaussianSumFilter/GsfBetheHeitlerEffects.h

-/*
-  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
-*/
-
-/**
- * @file   GsfBetheHeitlerEffects.h
- * @date   Friday 18th February 2005
- * @author Tom Athkinson, Anthony Morley, Christos Anastopoulos
- * @brief  Bethe-Heitler material effects for electrons, used in the GSF
- */
-
-#ifndef Trk_GsfBetheHeitlerEffects_H
-#define Trk_GsfBetheHeitlerEffects_H
-
-#include "AthenaBaseComps/AthAlgTool.h"
-#include "TrkEventPrimitives/ParticleHypothesis.h"
-#include "TrkEventPrimitives/PropDirection.h"
-#include "TrkGaussianSumFilter/GsfConstants.h"
-#include "TrkGaussianSumFilter/IBetheHeitlerEffects.h"
-#include "TrkMultiComponentStateOnSurface/MultiComponentState.h"
-#include <array>
-namespace Trk {
-
-class GsfBetheHeitlerEffects
-  : public AthAlgTool
-  , virtual public IBetheHeitlerEffects
-{
-
-public:
-  struct ComponentValues
-  {
-    double weight;
-    double mean;
-    double variance;
-  };
-
-  using MixtureParameters =
-    std::array<ComponentValues, GSFConstants::maxNumberofBHComponents>;
-
-  /** Helper class for construction and evaluation of polynomial */
-  struct Polynomial
-  {
-    // Evaluation of the polynomial for given material thickness (t)
-    double operator()(const double& t) const
-    {
-      double sum(0.);
-      for (size_t i = 0; i < GSFConstants::polynomialCoefficients; ++i) {
-        sum = t * sum + coefficients[i];
-      }
-      return sum;
-    }
-    std::array<double, GSFConstants::polynomialCoefficients> coefficients;
-  };
-
-  GsfBetheHeitlerEffects(const std::string&,
-                         const std::string&,
-                         const IInterface*);
-
-  virtual ~GsfBetheHeitlerEffects() = default;
-
-  /** AlgTool initialise method */
-  virtual StatusCode initialize() override final;
-
-  virtual void compute(Trk::GSFEnergyLossCache& cache,
-                       const ComponentParameters& componentParameters,
-                       const MaterialProperties& materialProperties,
-                       double pathLenght,
-                       PropDirection direction = anyDirection,
-                       ParticleHypothesis particleHypothesis =
-                         nonInteracting) const override final;
-
-private:
-  // Read polynomial fit parameters from a specified file
-  bool readParameters();
-
-  std::array<Polynomial, GSFConstants::maxNumberofBHComponents>
-    m_polynomialWeights;
-  std::array<Polynomial, GSFConstants::maxNumberofBHComponents>
-    m_polynomialMeans;
-  std::array<Polynomial, GSFConstants::maxNumberofBHComponents>
-    m_polynomialVariances;
-  std::array<Polynomial, GSFConstants::maxNumberofBHComponents>
-    m_polynomialWeightsHighX0;
-  std::array<Polynomial, GSFConstants::maxNumberofBHComponents>
-    m_polynomialMeansHighX0;
-  std::array<Polynomial, GSFConstants::maxNumberofBHComponents>
-    m_polynomialVariancesHighX0;
-
-  int m_numberOfComponents;
-  int m_transformationCode;
-  int m_correctionFlag;
-  int m_numberOfComponentsHighX0;
-  int m_transformationCodeHighX0;
-
-  double m_singleGaussianRange;
-  double m_lowerRange;
-  double m_xOverRange;
-  double m_upperRange;
-  double m_componentMeanCut;
-
-  bool m_useHighX0;
-  std::string m_parameterisationFileName;
-  std::string m_parameterisationFileNameHighX0;
-};
-
-}
-
-#endif