Many friendly operating systems have 64-bit times, and it's not nice
to pass them to an %ld format.

It's also extremely not-nice to write a time to the log as an
integer.  Most people think it's 2010 June 29 23:57 UTC+epsilon, not
1277855805+epsilon.

Possible workaround for bug 1139, if anybody cares.

Older versions of Libevent forgot to declare enough function arguments
constant.

These timers behave better with non-monotonic clocks than our old
ones, and also try harder to make once-per-second events get called
one second apart, rather than one-plus-epsilon seconds apart.

This fixes bug 943 for everybody using Libevent 2.0 or later.

Now people will have no excuse for not knowing what "MUST" and "MAY"
mean.  Fixes bug 1310.

From the code:
   zlib 1.2.4 and 1.2.5 do some "clever" things with macros.  Instead of
   saying "(defined(FOO) ? FOO : 0)" they like to say "FOO-0", on the theory
   that nobody will care if the compile outputs a no-such-identifier warning.

   Sorry, but we like -Werror over here, so I guess we need to define these.
   I hope that zlib 1.2.6 doesn't break these too.

Possible fix for bug 1526.

This should never happen unless openssl is buggy or some of our
assumptions are deeply wrong, but one of those might have been the
cause of the not-yet-reproducible bug 1209.  If it ever happens again,
let's get some info we can use.

We need to ensure that we close timeout measurement circuits. While
we're at it, we should close really old circuits of certain types that
aren't in use, and log really old circuits of other types.

We need to record different statistics at point of timeout, vs the point
of forcible closing.

Also, give some better names to constants and state file variables
to indicate they are not dealing with timeouts, but abandoned circuits.

Also clean up some log messages.

Thanks Roger for noticing

Fixes bug 1352

This is done to provide better data to our right-censored Pareto model.

We do this by simply marking them with a new purpose.

Histogram conversion causes accuracy loss, and there are some
boundary conditions when we hit 1000 circuits that cause
false negative test results.