enter editmode when adding objects even if the object is not in an active layer,

useful for python but in rare cases this also happens for users.

Active layer getting out of sync is an old bug but hard find when it happens.
This at least fixes segfaulting on adding objects.

source/blender/editors/include/ED_object.h

@@ -74,6 +74,7 @@ void ED_object_toggle_modes(struct bContext *C, int mode);
 #define EM_FREEUNDO		2
 #define EM_WAITCURSOR	4
 #define EM_DO_UNDO		8
+#define EM_IGNORE_LAYER	16
 void ED_object_exit_editmode(struct bContext *C, int flag);
 void ED_object_enter_editmode(struct bContext *C, int flag);