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.

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

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

Add config paths table in arti docs

See merge request tpo/core/arti!386

fix reproducible build summary giving invalid branch and commit id

Closes #378

See merge request tpo/core/arti!383

Errors for dirprovider

Closes #370

See merge request tpo/core/arti!385

fix #378
also fix unrelated error in nightly rustdoc CI

Replace many manual trait impls with use of educe

See merge request tpo/core/arti!375

Speed up RsaIdentity decoding

Closes #377

See merge request tpo/core/arti!381