Double-check semver breaks

[dbr]

Extension of #688 and #694 - double-check the semver breaks to check all are necessary, and if they can be smoothed

[dbr]

These were all pretty reasonable:

--- failure auto_trait_impl_removed: auto trait no longer implemented ---

Description:
A public type has stopped implementing one or more auto traits. This can break downstream code that depends on the traits being implemented.
        ref: https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits
       impl: https://github.com/obi1kenobi/cargo-semver-check/tree/v0.15.2/src/queries/auto_trait_impl_removed.ron

Failed in:
  type ImageButton is no longer UnwindSafe, in imgui/src/widget/image.rs:78
  type ImageButton is no longer Send, in imgui/src/widget/image.rs:78
  type ImageButton is no longer Sync, in imgui/src/widget/image.rs:78
  type ImageButton is no longer RefUnwindSafe, in imgui/src/widget/image.rs:78

Loss of these is fine - imgui stuff is generally non-Sync, the auto-traits were there because the old ImageButton was mostly an ~empty builder

---

--- failure enum_marked_non_exhaustive: enum marked #[non_exhaustive] ---

Description:
A public enum has been marked #[non_exhaustive]. Pattern-matching on it outside of its crate must now include a wildcard pattern like `_`, or it will fail to compile.
        ref: https://doc.rust-lang.org/reference/attributes/type_system.html#the-non_exhaustive-attribute
       impl: https://github.com/obi1kenobi/cargo-semver-check/tree/v0.15.2/src/queries/enum_marked_non_exhaustive.ron

Failed in:
  enum Key in imgui/src/input/keyboard.rs:9

Somewhat unavoidable

---

--- failure enum_variant_missing: pub enum variant removed or renamed ---

Description:
A publicly-visible enum has at least one variant that is no longer available under its prior name. It may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-check/tree/v0.15.2/src/queries/enum_variant_missing.ron

Failed in:
  variant Key::KeyPadEnter, previously in file /home/dbr/.cargo/registry/src/github.com-1ecc6299db9ec823/imgui-0.9.0/src/input/keyboard.rs:24

Avoidable but not worthwhile given the other changes in Key and the "did you mean" prompt in error

---

--- failure inherent_method_missing: pub method removed or renamed ---

Description:
A publicly-visible method or associated fn is no longer available under its prior name. It may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-check/tree/v0.15.2/src/queries/inherent_method_missing.ron

Failed in:
  ImageButton::frame_padding, previously in file /home/dbr/.cargo/registry/src/github.com-1ecc6299db9ec823/imgui-0.9.0/src/widget/image.rs:124

Technically breaking, but the ImageButtonDeprecated makes this generally backwards-compatible

---

--- failure method_parameter_count_changed: pub method parameter count changed ---

Description:
A publicly-visible method now takes a different number of parameters.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#fn-change-arity
       impl: https://github.com/obi1kenobi/cargo-semver-check/tree/v0.15.2/src/queries/method_parameter_count_changed.ron

Failed in:
  imgui::image::ImageButton::build now takes 1 parameters instead of 2, in imgui/src/widget/image.rs:166
       Final [  18.970s] semver requires new major version: 5 major and 0 minor checks failed

Same