Animation,Trade: add various TODOs.

The relatively older APIs don't have the usability as good as the recent
MeshData/MaterialData/SkinData. Gotta fix that.

src/Magnum/Animation/Track.h

@@ -549,6 +549,8 @@ template<class K, class V, class R
          * and to @cpp const std::pair<K_, V_> @ce (where @p K_ / @p V_ are
          * with @cpp const @ce removed) when they are @cpp const @ce.
          */
+        /** @todo drop this, supplying strided array views is the usual
+            workflow at this point */
         typedef typename std::conditional<std::is_const<K>::value, const std::pair<typename std::remove_const<K>::type, typename std::remove_const<V>::type>, std::pair<K, V>>::type KeyValueType;
 
         /** @brief Animation result type */
@@ -599,12 +601,16 @@ template<class K, class V, class R
          * Converts @p data to a pair of strided array views and calls
          * @ref TrackView(const Containers::StridedArrayView1D<K>&, const Containers::StridedArrayView1D<V>&, Interpolator, Extrapolation, Extrapolation).
          */
+        /** @todo drop this, supplying strided array views is the usual
+            workflow at this point */
         /*implicit*/ TrackView(Containers::ArrayView<KeyValueType> data, Interpolator interpolator, Extrapolation before, Extrapolation after) noexcept: TrackView<K, V, R>{Containers::StridedArrayView1D<K>{data, data ? &data[0].first : nullptr, data.size(), sizeof(std::pair<K, V>)}, Containers::StridedArrayView1D<V>{data, data ? &data[0].second : nullptr, data.size(), sizeof(std::pair<K, V>)}, interpolator, before, after} {}
 
         /** @overload
          * Equivalent to calling @ref TrackView(Containers::ArrayView<KeyValueType>, Interpolator, Extrapolation, Extrapolation)
          * with both @p before and @p after set to @p extrapolation.
          */
+        /** @todo drop this, supplying strided array views is the usual
+            workflow at this point */
         explicit TrackView(Containers::ArrayView<KeyValueType> data, Interpolator interpolator, Extrapolation extrapolation = Extrapolation::Constant) noexcept: TrackView<K, V, R>{data, interpolator, extrapolation, extrapolation} {}
 
         /**
@@ -641,12 +647,16 @@ template<class K, class V, class R
          * Converts @p data to a pair of strided array views and calls
          * @ref TrackView(const Containers::StridedArrayView1D<K>&, const Containers::StridedArrayView1D<V>&, Interpolator, Extrapolation, Extrapolation).
          */
+        /** @todo drop this, supplying strided array views is the usual
+            workflow at this point */
         /*implicit*/ TrackView(Containers::ArrayView<KeyValueType> data, Interpolation interpolation, Interpolator interpolator, Extrapolation before, Extrapolation after) noexcept: TrackViewStorage<K>{Containers::StridedArrayView1D<K>{data, data ? &data[0].first : nullptr, data.size(), sizeof(std::pair<K, V>)}, Containers::StridedArrayView1D<V>{data, data ? &data[0].second : nullptr, data.size(), sizeof(std::pair<K, V>)}, interpolation, interpolator, before, after} {}
 
         /** @overload
          * Equivalent to calling @ref TrackView(Containers::ArrayView<KeyValueType>, Interpolation, Interpolator, Extrapolation, Extrapolation)
          * with both @p before and @p after set to @p extrapolation.
          */
+        /** @todo drop this, supplying strided array views is the usual
+            workflow at this point */
         /*implicit*/ TrackView(Containers::ArrayView<KeyValueType> data, Interpolation interpolation, Interpolator interpolator, Extrapolation extrapolation = Extrapolation::Constant) noexcept: TrackView<K, V, R>{data, interpolation, interpolator, extrapolation, extrapolation} {}
 
         /**
@@ -681,12 +691,16 @@ template<class K, class V, class R
          * Converts @p data to a pair of strided array views and calls
          * @ref TrackView(const Containers::StridedArrayView1D<K>&, const Containers::StridedArrayView1D<V>&, Interpolator, Extrapolation, Extrapolation).
          */
+        /** @todo drop this, supplying strided array views is the usual
+            workflow at this point */
         /*implicit*/ TrackView(Containers::ArrayView<KeyValueType> data, Interpolation interpolation, Extrapolation before, Extrapolation after) noexcept: TrackView<K, V, R>{Containers::StridedArrayView1D<K>{data, data ? &data[0].first : nullptr, data.size(), sizeof(std::pair<K, V>)}, Containers::StridedArrayView1D<V>{data, data ? &data[0].second : nullptr, data.size(), sizeof(std::pair<K, V>)}, interpolation, before, after} {}
 
         /** @overload
          * Equivalent to calling @ref TrackView(Containers::ArrayView<KeyValueType>, Interpolation, Extrapolation, Extrapolation)
          * with both @p before and @p after set to @p extrapolation.
          */
+        /** @todo drop this, supplying strided array views is the usual
+            workflow at this point */
         /*implicit*/ TrackView(Containers::ArrayView<KeyValueType> data, Interpolation interpolation, Extrapolation extrapolation = Extrapolation::Constant) noexcept: TrackView<K, V, R>{data, interpolation, extrapolation, extrapolation} {}
 
         /** @brief Convert a mutable view to a const one */

src/Magnum/Trade/AbstractImporter.cpp

@@ -429,6 +429,8 @@ Containers::Optional<AnimationData> AbstractImporter::animation(const UnsignedIn
     CORRADE_ASSERT(isOpened(), "Trade::AbstractImporter::animation(): no file opened", {});
     CORRADE_ASSERT(id < doAnimationCount(), "Trade::AbstractImporter::animation(): index" << id << "out of range for" << doAnimationCount() << "entries", {});
     Containers::Optional<AnimationData> animation = doAnimation(id);
+    /** @todo maybe this should also disallow custom interpolators? since thise
+        would be dangling on plugin unload */
     CORRADE_ASSERT(!animation ||
         ((!animation->_data.deleter() || animation->_data.deleter() == static_cast<void(*)(char*, std::size_t)>(Implementation::nonOwnedArrayDeleter) || animation->_data.deleter() == ArrayAllocator<char>::deleter) &&
         (!animation->_tracks.deleter() || animation->_tracks.deleter() == static_cast<void(*)(AnimationTrackData*, std::size_t)>(Implementation::nonOwnedArrayDeleter))),

src/Magnum/Trade/AnimationData.h

@@ -280,6 +280,9 @@ class AnimationTrackData {
          * @param target        Track target
          * @param view          Type-erased @ref Animation::TrackView instance
          */
+        /** @todo stop taking TrackViewStorage and instead directly take the
+            key/value views, interpolator/interpolation and extrapolation --
+            it's just 6 overloads and makes usage much better */
         explicit AnimationTrackData(AnimationTrackType type, AnimationTrackType resultType, AnimationTrackTargetType targetType, UnsignedLong target, Animation::TrackViewStorage<const Float> view) noexcept: _type{type}, _resultType{resultType}, _targetType{targetType}, _target{target}, _view{view} {}
 
         /** @overload

src/Magnum/Trade/LightData.h

@@ -121,6 +121,7 @@ class MAGNUM_TRADE_EXPORT LightData {
          * @brief Light type
          *
          * @see @ref type()
+         * @todo move this to LightType outside of the class for consistency
          */
         enum class Type: UnsignedByte {
             /* Zero reserved for an invalid value */

src/Magnum/Trade/SkinData.h

@@ -90,6 +90,8 @@ template<UnsignedInt dimensions> class SkinData {
         /** @brief Move assignment */
         SkinData<dimensions>& operator=(SkinData<dimensions>&& other) noexcept;
 
+        /** @todo expose DataFlags (so users can know if the data are externally owned, at least) */
+
         /**
          * @brief Joint IDs
          *