Don't discard all circuits every MaxCircuitDirtiness, because the
user might legitimately have set that to a very lower number.

Also don't use up all of our idle circuits with testing circuits,
since that defeats the point of preemptive circuits.

[Do not take conflicting change to rendclient.c]

And also the number of recent circuits used to decide
when the network changes.

We want it to be under our control so it doesn't mess
up initialization. This is likely the cause for
the bug the previous assert-adding commit (09a75ad3) was
trying to address.

Got a negative timeout value on startup. Need to narrow it down.

Also use bin midpoints for time values.

It seems to fire because of precision issues. Added
more debug info to the warn to try to figure out for sure.

Also change the max timeout quantile to 0.98, so we can
avoid huge synthetic timeout values.

Also correct some typos.

Using CircuitBuildTimeout is prone to issues with SIGHUP, etc.
Also, shuffle the circuit build times array after loading it
in so that newer measurements don't replace chunks of
similarly timed measurements.

Also switch Xm calculation to mode, not min.

It was compiling, but causing segfaults.

Also, adjust when the timer starts for new test circs
and save state every 25 circuits.

Also add code to keep creating circuits every minute until we
hit our minimum threshhold.

We need to also call it if we're going to calculate alpha
after a normal circuit build.