message: Remove commented to_matrix(blendshapes) code
  This is now done inside the fitting loop, but I don't think it's a performance hotspot. If it is, we can always profile and optimise this.
diff: @@ -346,8 +346,6 @@ inline std::pair<core::Mesh, fitting::RenderingParameters> fit_shape_and_pose(
  expression_coefficients.resize(blendshapes.size());
  }*/
  - // const MatrixXf blendshapes_as_basis = morphablemodel::to_matrix(blendshapes);
  -
  // Current mesh - either from the given coefficients, or the mean:
  VectorXf current_pca_shape = morphable_model.get_shape_model().draw_sample(pca_shape_coefficients);
  assert(morphable_model.has_separate_expression_model()); // Note: We could also just skip the expression fitting in this case.
  @@ -621,8 +619,6 @@ fit_shape_and_pose(const morphablemodel::MorphableModel& morphable_model,
  expression_coefficients.resize(blendshapes.size());
  }*/
  - // const MatrixXf blendshapes_as_basis = morphablemodel::to_matrix(blendshapes);
  -
  // Current mesh - either from the given coefficients, or the mean:
  VectorXf current_pca_shape = morphable_model.get_shape_model().draw_sample(pca_shape_coefficients);
  assert(morphable_model.has_separate_expression_model()); // Note: We could also just skip the expression fitting in this case.
  