added popup for handling SIGSEGV or SIGFPE

the popup is placed on each of the virtual screens
the user can decide to restart or quit i3
in case of an exit a core-dump is generated

include/util.h

@@ -150,6 +150,13 @@ void switch_layout_mode(xcb_connection_t *conn, Container *container, int mode);
 Client *get_matching_client(xcb_connection_t *conn,
                             const char *window_classtitle, Client *specific);
 
+/*
+ * Restart i3 in-place
+ * appends -a to argument list to disable autostart
+ *
+ */
+void i3_restart();
+
 #if defined(__OpenBSD__)
 /* OpenBSD does not provide memmem(), so we provide FreeBSD’s implementation */
 void *memmem(const void *l, size_t l_len, const void *s, size_t s_len);