Remove Dictionary include with forward declarations

modules/base/rendering/modelgeometry.cpp

@@ -28,6 +28,7 @@
 #include <openspace/util/factorymanager.h>
 #include <ghoul/filesystem/cachemanager.h>
 #include <ghoul/filesystem/filesystem.h>
+#include <ghoul/misc/dictionary.h>
 
 #include <fstream>
 

modules/base/rendering/modelgeometry.h

@@ -28,7 +28,8 @@
 #include <openspace/properties/propertyowner.h>
 
 #include <modules/base/rendering/renderablemodel.h>
-#include <ghoul/misc/dictionary.h>
+
+namespace ghoul { class Dictionary; }
 
 namespace openspace {
 namespace documentation {  struct Documentation; }