NULL out conns on tlschans when freeing in case channel_run_cleanup() is late; fixes bug 9602
Attribute bug 9602 to a version.
Merge remote-tracking branch 'origin/maint-0.2.4'
Discard circuit paths on which nobody supports ntor

Right now this accounts for about 1% of circuits over all, but if you
pick a guard that's running 0.2.3, it will be about 6% of the circuits
running through that guard.

Making sure that every circuit has at least one ntor link means that
we're getting plausibly good forward secrecy on every circuit.

This implements ticket 9777,
Merge remote-tracking branch 'public/feature9777_024_squashed'

Conflicts:
	src/or/circuitbuild.c
Merge the circuit_{free,clear}_cpath functions

(Based on a suggestion by arma at #9777)