Add basic QSettings wrapper

[direc85]

Upstream-compatible version of https://github.com/whisperfish/qmetaobject-rs/pull/2

---

Attempt of adding QSettings wrapper. This was a bit tricky because QSettings can't be copied, so we have to return QSettings * instead, and handle the dereference in the client. This leads into having these in the use-side implementation, but there's no obvious way to get rid of that to me:

fn inner(&self) -> &QSettings {
    unsafe { self.inner_ptr.as_ref().unwrap() }
}

fn inner_mut(&mut self) -> &mut QSettings {
    unsafe { self.inner_ptr.as_mut().unwrap() }
}

[rubdos]

https://github.com/woboq/qmetaobject-rs/actions/runs/4649514331/jobs/8227901989?pr=285 interesting.

[direc85]

Interesting indeed. Something about Windows and tempfile, I guess. I have a Windows 'puter somewhere still, so I can see what's up with that.

[direc85]

It turned out to be a combination of default file extension being .ini (on all platforms?) and Linux conveniently using IniFormat when set to NativeFormat.

I must also say that it would have been convenient to have all tests run to completion even if one test fails. Could that be changed in the future? Thanks...

[direc85]

This just became a blocker to Whisperfish for using master now that we have Rust 1.72 - thanks to the marvelous efforts of @rubdos - so could this please be merged to master? Thanks!

[ogoffart]

sorry, i didn't see the updated patch.

[direc85]

No worries! Thank you!