Shapes: added TODOs.

src/Shapes/Capsule.h

@@ -42,7 +42,7 @@ Unlike other elements the capsule doesn't support asymmetric scaling. When
 applying transformation, the scale factor is averaged from all axes. See
 @ref shapes for brief introduction.
 @see Capsule2D, Capsule3D
-@todo Assert for asymmetric scaling
+@todo Assert for asymmetric scaling to avoid costly sqrt?
 */
 template<UnsignedInt dimensions> class MAGNUM_SHAPES_EXPORT Capsule {
     public:

src/Shapes/Plane.h

@@ -39,6 +39,7 @@ namespace Magnum { namespace Shapes {
 @brief Infinite plane, defined by position and normal (3D only)
 
 See @ref shapes for brief introduction.
+@todo Assert for uniform scaling to avoid costly normalization?
 */
 class MAGNUM_SHAPES_EXPORT Plane {
     public:

src/Shapes/Sphere.h

@@ -42,7 +42,7 @@ Unlike other elements the sphere doesn't support asymmetric scaling. When
 applying transformation, the scale factor is averaged from all axes. See
 @ref shapes for brief introduction.
 @see Sphere2D, Sphere3D
-@todo Assert for asymmetric scaling
+@todo Assert for asymmetric scaling to avoid costly sqrt?
 */
 template<UnsignedInt dimensions> class MAGNUM_SHAPES_EXPORT Sphere {
     public: