derive Clone, PartialEq, Debug for native structs

[vortexofdoom]

Ignore branch name. Closes #404

[GodotRust]

API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-587

[Bromeon]

Thanks for your contribution! 🙂

Could you maybe add 3 #[itest] functions in native_structures_test.rs? One for each trait.

Each test could use a different native structure (but one per test is enough).

[vortexofdoom]

Added! Included ObjectId for debug since it was simplest to write out manually, otherwise used existing constructors.

[Bromeon]

Last feedback round:

• run rustfmt
• end comments with full stop (.) when possible
• combine the 2 commits to a single one (following Contributing.md)

Thanks! 🙂

[Bromeon]

To combine commits to one, a simple approach is:

git reset --soft master
git commit -am "message"
git push --force-with-lease

Make sure you keep the --soft!

[vortexofdoom]

Thanks! I kept missing steps.

[vortexofdoom]

Goofed, thanks for the patience.

[Bromeon]

Thanks a lot for your first PR! 😊