port to gtk 0.15

[emmanueltouzery]

Hello, I've ported all that I could find to gtkrs 0.15.0. I've mostly just checked that everything builds, ran only a few tests and in a basic way.

[antoyo]

Thanks a lot!

It seems there are some issues with the CI, where it cannot fetch the Ubuntu repositories.

[emmanueltouzery]

I think the ubuntu release was just end of life. I "downgraded" from 20.10 to 20.04, but 20.04 is LTS.

[emmanueltouzery]

i'll upgrade the rust version. gtkrs says they support only as far back as 1.56: https://github.com/gtk-rs/gtk3-rs#minimum-supported-rust-version

[emmanueltouzery]

Ok, now clippy fails due to:

    Checking relm v0.22.0 (/__w/relm/relm)
error: missing `#[must_use]` attribute on a method returning `Self`
  --> src/core/mod.rs:72:5
   |
72 | /     pub fn stream(&self) -> Self {
73 | |         self.clone()
74 | |     }
   | |_____^
   |
   = note: `-D clippy::return-self-not-must-use` implied by `-D warnings`
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#return_self_not_must_use

I'd say the hint is correct? And that we should add the must_use? What do you think? I'll add it now, we can revert this later if it doesn't make sense.

[antoyo]

Thanks a lot!

[antoyo]

Oops. I forgot to check that the version of the crates were updated and they weren't. Could you please make a new PR updating them so that I can publish the new versions?