fix segfault when iks base requested on start is absent

+ if an iks base (e.g. given using -base and an invalid ip address) was absent on draw3 startup, and we chose not to try again connecting, draw3 would segfault on set-prober-address query
+ now we launch a draw3 instance with no data (and if the user clicks inside data widget, draw3 will fail on runtime assertion: "Cannot set invalid time!"), this behavior is consistent with the behavior when we open an absent base in a new tab