Math: remove Frustum::planes() deprecated in 2019.10.

doc/changelog.dox

@@ -1761,6 +1761,9 @@ See also:
         @ref std::tuple typedefs and @ref Math::Color3::fromHsv() /
         @ref Math::Color4::fromHsv() overloads taking separate hue, saturation
         and value arguments. Use the @ref Math::ColorHsv struct instead.
+    -   @cpp Math::Frustum::planes() @ce, use @ref Math::Frustum::data() or
+        @relativeref{Math::Frustum,begin()} / @relativeref{Math::Frustum,end()}
+        instead
     -   @cpp Math::swizzle() @ce, use @ref Math::gather() instead
     -   @cpp Text::FontFeature::MultiFile @ce,
         @cpp Text::AbstractFont::openData() @ce taking a vector of pairs, and

src/Magnum/Math/Frustum.h

@@ -42,10 +42,6 @@
 #include "Magnum/Math/Matrix4.h"
 #include "Magnum/Math/Vector4.h"
 
-#ifdef MAGNUM_BUILD_DEPRECATED
-#include <Corrade/Containers/ArrayView.h> /** @todo remove when planes() is gone */
-#endif
-
 #ifdef CORRADE_TARGET_WINDOWS /* I so HATE windef.h */
 #undef near
 #undef far
@@ -165,18 +161,6 @@ template<class T> class Frustum {
         }
         #endif
 
-        #ifdef MAGNUM_BUILD_DEPRECATED
-        /**
-         * @brief Frustum planes
-         * @m_deprecated_since{2019,10} Use @ref operator[](std::size_t) const,
-         *      @ref data() or @ref begin() / @ref end() instead.
-         */
-        constexpr CORRADE_DEPRECATED("use operator[](), data() or begin() / end() instead") Containers::StaticArrayView<6, const Vector4<T>> planes() const {
-            /* GCC 4.8 needs explicit construction */
-            return Containers::StaticArrayView<6, const Vector4<T>>{_data};
-        }
-        #endif
-
         /**
          * @brief Plane at given index
          * @m_since{2020,06}