By calling circuit_n_chan_done() unconditionally on close, we were
closing pending connections that might not have been pending quite for
the connection we were closing.  Fix for bug 9880.

Thanks to skruffy for finding this and explaining it patiently until
we understood.

This avoids skew warnings as authorities test reachability.

Fix 9798; fix not on any released Tor.

this was causing directory authorities to send a time of 0 on all
connections they generated themselves, which means everybody reachability
test caused a time skew warning in the log for that relay.

(i didn't just revert, because the changes file has been modified by
other later commits.)

Implements part of proposal 222.  We can do this safely, since
REND_CACHE_MAX_SKEW is 24 hours.

This isn't actually much of an issue, since only relays send
AUTHENTICATE cells, but while we're removing timestamps, we might as
well do this too.

Part of proposal 222.  I didn't take the approach in the proposal of
using a time-based HMAC, since that was a bad-prng-mitigation hack
from SSL3, and in real life, if you don't have a good RNG, you're
hopeless as a Tor server.

For now, round down to the nearest 10 minutes.  Later, eliminate entirely by
setting a consensus parameter.

(This rounding is safe because, in 0.2.2, where the timestamp mattered,
REND_REPLAY_TIME_INTERVAL was a nice generous 60 minutes.)

Implements part of proposal 222.

we skip onionskins that came from non-relays, so we're less likely to
run into privacy troubles.

starts to implement ticket 9658.

Now we explicitly check for overflow.

This approach seemed smarter than a cascade of "change int to unsigned
int and hope nothing breaks right before the release".

Nick, feel free to fix in a better way, maybe in master.

with commit c6f1668d we let it grow arbitrarily large.

it can still overflow, but the damage is very small now.

Now we consider the TAP cells we'll process while draining the NTor
queue, and vice versa.

that way tap won't starve entirely, but we'll still handle ntor requests
quicker.

Now we prioritize ntor create cells over tap create cells.

Starts to address ticket 9574.

Conflicts:
	src/or/circuitbuild.c

This would make us do testing circuits "even when cbt is disabled by
consensus, or when we're a directory authority, or when we've failed
to write cbt history to our state file lately." (Roger's words.)

This is a fix for 9671 and an improvement in our fix for 5049.
The original misbehavior was in 0.2.2.14-alpha; the incomplete
fix was in 0.2.3.17-beta.

Fix for bug 9400, spotted by coverity. Bug introduced in revision 2cb4f7a4
(subversion revision r389).

(Using "ours" strategy to avoid taking 9546 fix in 0.2.3; we just
merged our own into 0.2.4)

Fix for bug 9564; bugfix on 0.2.3.14-alpha.