October was the date Torv2 is no longer supported by the Tor Project;
it will probably not work at all by next release, so we should remove
it now even though it's not quite the 6 months we prefer for
deprecation cycles.
I still see 110 nodes advertizing Torv2 (vs 10,292 Torv3); we still
parse and display it, we just don't advertize or connect to it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>