Clients are now verified to work and build circuits correctly.  There
are still a few warnings given here and there that I need to look into.

This was possible if we have already decided to close a bufferevent
connection, but the other side decides to close it first.

Also, set directory connections (linked and otherwise) to use bufferevents.

Also, stop using outbuf_flushlen anywhere except for OR connections.

These are based strongly on connection_handle_read and
connection_handle_write, but hopefully without so much mixture of IO
logic and Tor logic.

Now all of the logic is in a parse_socks() function that gets data
from a buf_t or evbuffer-specific wrapper.

{Make sure that if we have a bufferevent on a connection, we do not have the
other libevent/buffering-related fields set.}

Add an --enable-bufferevents config switch.

We'll get this feature for free with bufferevents, so there's no good reason
to clone it in Tor.

Cases 1 and 3b are provably correct. Case 2b has a fallback to first try to
maximize entropy.

The autoreconf tool deals much better with detecting which tools to
use on your particular platform, handling cases where your
install-sh script gets stable, and lots of other little tricky
issues.

We still fall back to autoconf&&automake&&etc in the case where
"`which autoreconf 2>/dev/null`" says something we can't run.

This is the first change of the 0.2.3.x series.

0.2.2.x development will continue in branch maint-0.2.2.

master is now out of feature freeze.

Let's not go crazy right away. :)

I think there was a read-off-the-end-of-the-buffer bug that I fixed.
At least I added some good comments, I hope.

We want to make sure that we don't break old torrc files that might have
used something like this made-up example:

    ContactInfo UberUser <uber@user.com> # /// Fake email! \\\
    Log info file /home/nick.mathewson/projects/tor-info.log

And we also want to support the following style of writing your torrc:

    ExcludeNodes \
    # Node1337 is run by the Bavarian Illuminati
      Node1337, \
    # The operator of Node99 looked at me funny
      Node99

The code already handles both cases, but the unit test should help prove
it.

Also redocument it.  Related to #1362.