When the version is a Tor version, we can just parse it; otherwise,
we can intern it.  This shrinks GenericRouterStatus and avoids a lot
of extra help allocations.

This is the default vscode format, and seems popular elsewhere.
This commit does nothing but reformat.

Part of #387

Follow-up from arti!318

See merge request tpo/core/arti!402

Make update_config only conditionally exported; add semver-status update.

Add flatfile DirMgr

See merge request tpo/core/arti!318

tests/chutney: Merge chutney-launching scripts

See merge request tpo/core/arti!396

It turns out that the clone-and-hack in tests/chutney/arti-bench
was not identical to the original in tests/chutney/setup.

I diffed the two and preferred the version from arti-bench.

Formerly, the "launch a chutney network" code was duplicated in
"setup" and "arti-bench", since "setup" always launched an arti
proxy, while "arti-bench" didn't want that functionality.

Now the "setup" script launches an arti proxy conditionally,
depending on whether the "proxy" argument is given.

Drop config back-conversion from FooConfig to FooConfigBuilder

See merge request tpo/core/arti!391

arti-testing: support for simulated TCP breakage

See merge request tpo/core/arti!392

arti-bench: don't allocate a separate receive-buffer for each job

Closes #391

See merge request tpo/core/arti!395

tor-chanmgr: Do not allocate an Internal error unless we mean it.

Closes #383

See merge request tpo/core/arti!394

This makes heap profiling more viable.

Closes #391.

Previously we'd allocate an error as a place-holder here, but it's
not a great idea to do that with a `Bug`: each `Bug` stores a whole
stack trace, which uses a whole pile of allocations to construct.

Now we keep an `Option<Error>` instead.

Found while heap profiling.

Closes #383.

Note the dependency on PCRE support in Git implied by the use of grep -P in the git hooks

See merge request tpo/core/arti!393

Add missing dependencies to CONTRIBUTING.md

See merge request tpo/core/arti!389

Fix expand tilde and invalid path chars on windows

See merge request tpo/core/arti!274

Add instructions for hooking up Tor Browser to arti on Windows

See merge request tpo/core/arti!388

Replace the recapitulation of TorClientConfig fields in ArtiConfig and
instead just have it contain one.  This is part of #374.

The conversions from ArtiConfig back to ArtiConfigBuilder and
TorClientConfigBuilder would need to change, but, since we don't want
them anyway,

No longer impl Deserialize for ArtiConfig.  (As per #371 this will
want to become a private type.)

No longer impl From<ArtiConfig> for ArtiConfigBuilder and
TorClientConfigBuilder.  And abolish tests of that code.

(This all has to be in one commit, because previously
ArtiConfig::tor_client_config used the validated-to-builder config
retcon.)

This is needed according to #372, where we observe that builders ought
not to be generated from validated structs.  So we need this
conversion.

I used
  git-grep -P '\#\[serde\((?!default|deny_unknown)'
to find places where I needed to add additional attributes on the
builder method fields.

This is currently a bit duplicative, but when #371 is completely done,
the validated (non-builder) configs won't need to be Deserialize any
more.

This is part of #371 and #372.

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.

Implement a basic form of RFC 8305 ("happy eyeballs") for channels

See merge request tpo/core/arti!382

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 makes Arti usable in IPv6-only environments (arti#92) by letting us
attempt multiple connections to a given relay using all of its
addresses instead of just using the first (probably IPv4) one, using the
strategy from RFC 8305 § 5.

This isn't a complete implementation of Happy Eyeballs; ideally, we'd
sort the address list before doing concurrent connections. However, it
works (and has been tested inside an IPv6-only container inside eta's
network :p)

arti-bench: support multiple streams per circuit, multiple circuits per sample.

Closes #380

See merge request tpo/core/arti!384