Latest clippy gained a warning lint about this:

```
error: variables can be used directly in the `format!` string
   --> zbus_macros/src/proxy.rs:199:30
    |
199 |             .or_else(|| Some(format!("/org/freedesktop/{}", ident)));
    |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
help: change this to
    |
199 -             .or_else(|| Some(format!("/org/freedesktop/{}", ident)));
199 +             .or_else(|| Some(format!("/org/freedesktop/{ident}")));
    |
```

Luckily, clippy can fix it automatically for us as well.

This fixes a clippy warning:

```
warning: you are deriving `PartialEq` and can implement `Eq`
   --> zbus/src/fdo.rs:452:57
    |
452 | #[derive(Deserialize_repr, Serialize_repr, Type, Debug, PartialEq)]
    |                                                         ^^^^^^^^^ help: consider deriving `Eq` as well: `PartialEq, Eq`
```

For some of the types, we had to ignore the warning due to:

https://github.com/rust-lang/rust-clippy/issues/8970

Rust seems to be really good at handling the name collision between the
types and the macros so there is no need for an extra module for the
re-export.

Since async is now the primary API, let's generate the shorter name for
the async proxies and longer one for blocking ones.

No idea why we took them by value, perhaps it didn't work at that time.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

This is to ensure that these string types are checked for conformance.
We should do that anyway but the D-Bus specification also mandates
implementations to verify everything to and from the bus.

While generic implementations and `TryFrom` implementations ensure that
impact to users is minimum with this change, unfortunately they do now
have to specify type when passing a `None` value. This howeover is a
well-known pain-point in the Rust world and nothing specific to zbus.

Our currently solution is close to what will come in the future with `!`
types: https://github.com/rust-lang/rust/issues/35121 .

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Closes #140.

Following clippy advise to get rid of extra if let Ok().

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

And fix all the issues.

This makes use of our new signal handling API.

This is a convenience function for construction a Subject from a
MessageHeader for querying if the sender of a Message is permitted to
execute an action.

Since we're going for the macros as our recommended API, it makes sense
to re-export the zbus_derive macros in zbus for convenience:

Fixes #38

This should demonstrate how to bind a DBus API, while being very useful!