message: No need for prefilterable texture base class
  We don't use that code path anyway
diff: @@ -232,48 +232,6 @@ protected:
  };
  -template <typename T, typename Derived>
  -class prefilterable
  -{
  -public:
  -
  - typedef T value_type;
  - typedef short element_type;
  -
  - element_type* prefiltered_data;
  -
  -
  - prefilterable() : prefiltered_data(0), filter_mode_(Nearest) {}
  -
  - void set_filter_mode(tex_filter_mode mode)
  - {
  - if (mode == BSplineInterpol)
  - {
  - Derived* d = static_cast<Derived*>(this);
  -
  - prefiltered_.resize( d->size() );
  - prefiltered_data = &prefiltered_[0];
  - std::transform(
  - &(d->data)[0],
  - &(d->data)[d->size()],
  - prefiltered_.begin(),
  - [](value_type val) { return static_cast<element_type>(val); }
  - );
  - convert_for_bspline_interpol( d );
  - }
  -
  - filter_mode_ = mode;
  - }
  -
  - tex_filter_mode get_filter_mode() const { return filter_mode_; }
  -
  -protected:
  -
  - tex_filter_mode filter_mode_;
  - aligned_vector<element_type> prefiltered_;
  -
  -};
  -
  template <typename T>
  VSNRAY_FUNC
  inline T apply_color_conversion(T const& t, tex_color_space const& color_space)
  