message: Fix compilation of keyframe merging
diff: #ifndef KEYFRAME_MERGING_HPP_
  #define KEYFRAME_MERGING_HPP_
  -#include "eos/fitting/FittingResult.hpp"
  -#include "eos/fitting/RenderingParameters.hpp"
  +#include "eos/core/Image_opencv_interop.hpp"
  #include "eos/morphablemodel/Blendshape.hpp"
  #include "eos/morphablemodel/MorphableModel.hpp"
  #include "eos/video/Keyframe.hpp"
  @@ -62,7 +61,7 @@ namespace video {
  * @param[in] blendshapes The blendshapes with which the keyframes have been fitted.
  * @return Merged texture map (isomap), 3-channel uchar.
  */
  -inline cv::Mat merge_weighted_mean(const std::vector<Keyframe>& keyframes,
  +inline cv::Mat merge_weighted_mean(const std::vector<Keyframe<cv::Mat>>& keyframes,
  const morphablemodel::MorphableModel& morphable_model,
  const std::vector<morphablemodel::Blendshape>& blendshapes)
  {
  @@ -85,8 +84,8 @@ inline cv::Mat merge_weighted_mean(const std::vector<Keyframe>& keyframes,
  {}, morphable_model.get_texture_coordinates());
  const auto affine_camera_matrix = fitting::get_3x4_affine_camera_matrix(
  frame_data.fitting_result.rendering_parameters, frame_data.frame.cols, frame_data.frame.rows);
  - const Mat isomap = render::extract_texture(mesh, affine_camera_matrix, frame_data.frame, true,
  - render::TextureInterpolation::NearestNeighbour, 1024);
  + const Mat isomap = core::to_mat(render::extract_texture(mesh, affine_camera_matrix, core::from_mat(frame_data.frame), true,
  + render::TextureInterpolation::NearestNeighbour, 1024));
  isomaps.push_back(isomap);
  }
  @@ -128,7 +127,7 @@ inline cv::Mat merge_weighted_mean(const std::vector<Keyframe>& keyframes,
  // accumulated_weight = (accumulated_weight / isomaps.size()) * 255;
  Mat merged_isomap;
  - cv::merge({b, g, r}, merged_isomap);
  + cv::merge(vector<Mat>{b, g, r}, merged_isomap);
  merged_isomap.convertTo(merged_isomap, CV_8UC3);
  return merged_isomap;
  };
  