message: Corrected PcaModel documentation
  It hasn't had a method to return a Mesh in quite a while I think.
diff: @@ -50,7 +50,6 @@ cv::Mat unnormalise_pca_basis(cv::Mat normalised_basis, cv::Mat eigenvalues);
  *
  * It also contains a list of triangles to built a mesh as well as a mapping
  * from landmark points to the corresponding vertex-id in the mesh.
  - * It is able to return instances of the model as meshes.
  */
  class PcaModel
  {
  