Hide forward declarations from Doxygen.

Forward declarations of templated types don't have named template
parameters and thus Doxygen (sometimes) used these for documentation. It
then looked like this:

    Magnum::Math::RectangularMatrix<std::size_t, std::size_t, class>

which isn't helpful at all. After the change it looks like this (much
better):

    Magnum::Math::RectangularMatrix<cols, rows, T>

src/Magnum/Audio/Audio.h

@@ -31,11 +31,13 @@
 
 namespace Magnum { namespace Audio {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 class AbstractImporter;
 class Buffer;
 class Context;
 class Source;
 /* Renderer used only statically */
+#endif
 
 }}
 

src/Magnum/DebugTools/DebugTools.h

@@ -33,6 +33,7 @@
 
 namespace Magnum { namespace DebugTools {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 template<UnsignedInt> class ForceRenderer;
 typedef ForceRenderer<2> ForceRenderer2D;
 typedef ForceRenderer<3> ForceRenderer3D;
@@ -50,6 +51,7 @@ template<UnsignedInt> class ShapeRenderer;
 typedef ShapeRenderer<2> ShapeRenderer2D;
 typedef ShapeRenderer<3> ShapeRenderer3D;
 class ShapeRendererOptions;
+#endif
 
 }}
 

src/Magnum/Magnum.h

@@ -45,10 +45,9 @@ typedef unsigned int GLenum; /* Needed for *Format and *Type enums */
 namespace Magnum {
 
 namespace Math {
-    template<class T> struct Constants;
-
-    /** @todoc Remove `ifndef` when Doxygen is able to handle operator"" */
     #ifndef DOXYGEN_GENERATING_OUTPUT
+    template<class> struct Constants;
+
     #ifndef MAGNUM_TARGET_GLES
     constexpr Rad<Double> operator "" _rad(long double);
     constexpr Deg<Double> operator "" _deg(long double);
@@ -441,6 +440,7 @@ using Math::operator "" _radf;
 
 /* Forward declarations for all types in root namespace */
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 /* FramebufferClear[Mask], FramebufferBlit[Mask], FramebufferBlitFilter,
    FramebufferTarget enums used only directly with framebuffer instance */
 class AbstractFramebuffer;
@@ -559,6 +559,7 @@ enum class TextureFormat: GLenum;
 class Timeline;
 
 enum class Version: Int;
+#endif
 
 }
 

src/Magnum/Math/Math.h

@@ -38,6 +38,7 @@ namespace Magnum { namespace Math {
 
 /** @todo Denormals to zero */
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 /* Class Constants used only statically */
 
 template<class> class Complex;
@@ -82,6 +83,7 @@ namespace Geometry {
     template<class> class Rectangle;
 }
 #endif
+#endif
 
 }}
 

src/Magnum/Platform/Platform.h

@@ -31,9 +31,11 @@
 
 namespace Magnum { namespace Platform {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 template<class> class BasicScreen;
 template<class> class BasicScreenedApplication;
 class Context;
+#endif
 
 }}
 

src/Magnum/SceneGraph/SceneGraph.h

@@ -33,6 +33,7 @@
 
 namespace Magnum { namespace SceneGraph {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 enum class AspectRatioPolicy: UnsignedByte;
 
 template<UnsignedInt, class> class AbstractCamera;
@@ -152,6 +153,7 @@ typedef BasicTranslationTransformation3D<Float> TranslationTransformation3D;
 namespace Implementation {
     template<class> struct Transformation;
 }
+#endif
 
 }}
 

src/Magnum/Shaders/Shaders.h

@@ -33,6 +33,7 @@
 
 namespace Magnum { namespace Shaders {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 template<UnsignedInt> class DistanceFieldVector;
 typedef DistanceFieldVector<2> DistanceFieldVector2D;
 typedef DistanceFieldVector<3> DistanceFieldVector3D;
@@ -57,6 +58,7 @@ typedef Vector<3> Vector3D;
 template<UnsignedInt> class VertexColor;
 typedef VertexColor<2> VertexColor2D;
 typedef VertexColor<3> VertexColor3D;
+#endif
 
 }}
 

src/Magnum/Shapes/Shapes.h

@@ -33,6 +33,7 @@
 
 namespace Magnum { namespace Shapes {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 template<UnsignedInt> class AbstractShape;
 typedef AbstractShape<2> AbstractShape2D;
 typedef AbstractShape<3> AbstractShape3D;
@@ -88,6 +89,7 @@ class Plane;
 template<UnsignedInt> class Point;
 typedef Point<2> Point2D;
 typedef Point<3> Point3D;
+#endif
 
 }}
 

src/Magnum/Text/Text.h

@@ -34,6 +34,7 @@
 
 namespace Magnum { namespace Text {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 class AbstractFont;
 class AbstractFontConverter;
 class AbstractLayouter;
@@ -51,6 +52,7 @@ typedef Renderer<3> Renderer3D;
 typedef Renderer<2> TextRenderer2D;
 typedef Renderer<3> TextRenderer3D;
 #endif
+#endif
 
 }}
 

src/Magnum/Trade/Trade.h

@@ -33,6 +33,7 @@
 
 namespace Magnum { namespace Trade {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 class AbstractImageConverter;
 class AbstractImporter;
 class AbstractMaterialData;
@@ -53,6 +54,7 @@ class ObjectData3D;
 class PhongMaterialData;
 class TextureData;
 class SceneData;
+#endif
 
 }}