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

core/os/memory.cpp

@@ -30,9 +30,9 @@
 
 #include "memory.h"
 
-#include "core/error_macros.h"
+#include "core/error/error_macros.h"
 #include "core/os/copymem.h"
-#include "core/safe_refcount.h"
+#include "core/templates/safe_refcount.h"
 
 #include <stdio.h>
 #include <stdlib.h>