Reorganized core/ directory, it was too fatty already

-Removed FuncRef, since Callable makes it obsolete
-Removed int_types.h as its obsolete in c++11+
-Changed color names code

scene/3d/skeleton_3d.cpp

@@ -30,10 +30,10 @@
 
 #include "skeleton_3d.h"
 
-#include "core/engine.h"
-#include "core/message_queue.h"
-#include "core/project_settings.h"
-#include "core/type_info.h"
+#include "core/config/engine.h"
+#include "core/config/project_settings.h"
+#include "core/object/message_queue.h"
+#include "core/variant/type_info.h"
 #include "scene/3d/physics_body_3d.h"
 #include "scene/resources/surface_tool.h"
 #include "scene/scene_string_names.h"