this also removes JoinResult

This has the different syntax for builder field attributes than what I
originally proposed in my MR, and which therefore is in the pinned
branch.

My upstream MR for the field attributes feature was morged:
  https://github.com/colin-kiegel/rust-derive-builder/issues/239

This (almost) a pure code-movement commit: it also makes one public
function private in order to suppress a warning.

We have upstreamed this code.

This reverts commit 6193c9d9.

This has the humantime_serde::option module, which we have upstreamed
and are about to switch to.

The remaining dependency with  version = "1"  is going to be removed
in a moment.

This enum was otiose: its set of valid values is precisely those of a
Vec.  (Indeed what would TokVal::Multi(vec![]) have meant?)

We are going to want to specify custom attributes on fields of the
builder struct.  This feature was missing from derive_builder.

This commitid is the current head of my MR branch
  https://github.com/colin-kiegel/rust-derive-builder/pull/237
  https://github.com/ijackson/rust-derive-builder/tree/builder-field-attrs
Using the commitid prevents surprises if that branch is updated.

We will require this newer version of derive_builder.  The version
will need to be bumped again later, assuming the upstream MR is merged
and upstream do a release containing the needed changes.

This commit adds support for a BrokenTcp provider that can make
connection attempts fail or time out.  It doesn't yet have a way to
turn on the failure.

This will be used to allow our config *builder* structs to be
Deserialize.

Code motion and the minimal mechanical changes.

As per
  !375 (comment 2783078)

Empty crate right now

This commit adds a new program to try to implement the ideas behind
experimentation in arti#329.  In particular, it tries to implement
basic client "can I bootstrap and connect" functionality testing,
with a lot of instrumentation, and support for breaking things.

So far, the instrumentation is limited to counting TCP bytes and
connections, and counting events.  Still, this is enough to measure
behavior on some of the incorrect-clock tests.

NOTE:

For now, you are _required_ to pass in an explicit configuration, in
hopes that this will lead you to override your storage directories
for doing specific experiments.

We now print slighly more information.

Preparatory work for getting rid of some manual Debug impls

Apropos discussion in
  tpo/core/arti!274

Add tls_conn field to ArtiHttpConnector (and argument to constructor).
Introduce MaybeHttpsStream and use it in ArtiHttpConnection.
Have the example program pass the native TLS connector.

Currently the TLS connector and the HTTPS variant are not used, but
this commit is very noisy and fomrulaic, so I have split out the code
to use them into a separate commit for easier preparation and review.

(It's good to do this a couple of days in advance in case it turns
up any bugs.  That's how we caught the panic bug in simple_asn1
0.6.0)

We need this not to use anyhow because we don't want our libraries to
expose anyhow, and this is about to go into the library.

Code motion and consequential dependency adjustments.

This isn't complete (see TODO), but it's enough to let us report the
right ErrorKind if something fails to parse.

The new `BootstrapBehavior` enum controls whether an unbootstrapped
`TorClient` will bootstrap itself automatically (`Ondemand`) when an
attempt is made to use it, or whether the user must perform
bootstrapping themselves (`Manual`).

The `lazy-init` example shows how you could write a simple
`get_tor_client()` function that used a global `OnceCell` to share
a Tor client across an entire application with this API.

closes arti#278