Remanage window after property updates (like titles) (#3759)

include/manage.h

@@ -37,3 +37,10 @@ void restore_geometry(void);
 void manage_window(xcb_window_t window,
                    xcb_get_window_attributes_cookie_t cookie,
                    bool needs_to_be_mapped);
+
+/**
+ * Remanages a window: performs a swallow check and runs assignments.
+ * Returns con for the window regardless if it updated.
+ *
+ */
+Con *remanage_window(Con *con);