Removed "wontfix" TODOs.

Loop unrolling is better to leave up to the compiler, as it will do it
automatically and it doesn't add any maintenance burden. Constexpr
addition, multiplication etc. of Vector would be nice, but will that be
really useful? Maybe once if at all?

src/Math/Matrix.h

@@ -37,7 +37,6 @@ namespace Implementation {
 See @ref matrix-vector for brief introduction.
 
 @configurationvalueref{Magnum::Math::Matrix}
-@todo @c PERFORMANCE - loop unrolling for Matrix<3, T> and Matrix<4, T>
  */
 template<size_t s, class T> class Matrix: public RectangularMatrix<s, s, T> {
     public:

src/Math/Vector.h

@@ -41,7 +41,6 @@ namespace Implementation {
 
 See @ref matrix-vector for brief introduction.
 @configurationvalueref{Magnum::Math::Vector}
-@todo Constexprize all for loops
 */
 template<size_t s, class T> class Vector: public RectangularMatrix<1, s, T> {
     public: