This turns out to need quite a complicated algorithm.

This gets rid of `#[serde(flatten)]` which prevents serde_ignored (and
other kinds of introspection) from working properly.

The price is now that the toplevel has to deal with two configuration
objects.

The Resolvable trait is overkill right now, but is going to do More
Things in a moment.  In particular, we need the impl on tuples, so
that the whole config can be processed in one go.

We are going to need this for some generic code which is going to
appear shortly.  Having it produced by impl_standard_builder seems
best.  But that does mean being able to disable it, so extra stuff in
the macro.  Nothing uses this trait yet.

ConfigResolveError is not used now either, but will be in a moment.

We are going to reorganise ArtiConfig to not contain a
TorClientConfig.  This test case's calls to bld.tor() will all need to
change.  Do this in advance to make that future commit more readable.

I don't understand why this isn't tripping all the time.  Maybe
because this is in a macro.  Anyway, I am going to add a new
invocation of this macro from within a test where, empirically, it
trips.

Make file permissions configurable via regular config mechanisms

Closes #465

See merge request tpo/core/arti!515

This change requires a little refactoring of TorClientBuilder: now,
instead of enabling or disabling mistrust, it enables or disables
the decision to _override_ the mistrust in the config.

We support all of the following (in TOML notation):

```
user = "rose"  # by name
user = 413     # by ID
user = false   # no user
user = ":current"  # A 'special' user.

user = { name: "rose" }
user = { id: 413 }
user = { special: ":none" }
user = { special: ":current" }
```

The Group and User (de)serialization is pretty ugly, and I can't
vouch for the correcness of MistrustBuilder.  I will seek feedback
before I proceed.

This will help make the actual configuration more serializable,
I hope.

This is an approximately minimal revision to get Builder in place;
subsequent commits will clean up the API.

This renaming will make things slightly simpler for declaring a
builder.

Update to newer sanitize-filename and tinystr.

See merge request tpo/core/arti!523

Make clippy +nightly pass again

See merge request tpo/core/arti!522

It's a little overzealous sometimes, but it's mostly to the good.

These are warnings that we've decided it's okay to suppress elsewhere.

Remove dbg!()s in tor-config, and fix nightly CI

See merge request tpo/core/arti!516

async-compression minimum version 0.3.5 -> 0.3.14

Closes #473

See merge request tpo/core/arti!521

add unit tests for arti_client::StreamPrefs

See merge request tpo/core/arti!520

0.3.14 is the first released version to include
https://github.com/Nemo157/async-compression/commit/e7246738762de34bbb820662c3923f8f2610ac95,
which fixes tpo/core/arti#473

this change adds unit tests for the public methods of StreamPrefs. although
these are mostly "setter" style functions, the tests confirm the basic
expectations and operation.

channel: Provide and use Sink::prepare_send_from

See merge request tpo/core/arti!514

I think this is worse code, but it's not *significantly* worse.

I intend to reintroduce this in its own MR.

So we can change unwrap to expect, which makes this too long to repeat.

Apropos review.