Fixing more includes and forward declarations (#3876)

include/openspace/rendering/screenspacerenderableframebuffer.h

@@ -28,16 +28,12 @@
 #include <openspace/rendering/screenspacerenderable.h>
 
 #include <openspace/properties/vector/vec2property.h>
-
-namespace ghoul::opengl {
-    class FramebufferObject;
-    class Texture;
-} // namespace ghoul::opengl
+#include <ghoul/opengl/framebufferobject.h>
+#include <ghoul/opengl/texture.h>
+#include <functional>
 
 namespace openspace {
 
-namespace documentation { struct Documentation; }
-
 /**
  * Creates a texture by rendering to a framebuffer, this is then used on a screen space
  * plane. This class lets you add renderfunctions that should render to a framebuffer with