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

modules/gdnative/videodecoder/video_stream_gdnative.cpp

@@ -30,7 +30,7 @@
 
 #include "video_stream_gdnative.h"
 
-#include "core/project_settings.h"
+#include "core/config/project_settings.h"
 #include "servers/audio_server.h"
 
 VideoDecoderServer *VideoDecoderServer::instance = nullptr;