Scoping

[cyypherus]

This Approach:

• ✅ Fixes half baked scoping with the single state case
• ⚠️ Partial scoping is impossible given &mut Ui, &mut ViewStateIWantToScope

Multiple state generics: https://github.com/ejjonny/backer/tree/multistate

• ✅ Compiles without workarounds
• ✅ Enables partial scoping given &mut Ui, &mut ViewStateIWantToScope
• ⚠️ Really doesn't scale, maybe that's fine
• ⚠️ Noisy API to account for the single generic use case

Trait based scoping: https://github.com/ejjonny/backer/tree/trait-scoping

• ✅ Eliminates the need for AnyNode & related lifetime trouble
• ⚠️ Actually conforming to Scopable as a user seems to be complex or error prone due to some recursive conformance checks? I can't even get the partial scoping test to compile..
• ❌ Requires manual drop as a workaround for this issue
• ❌ Causes clippy eternal lint issue

[github-actions]

Commit: 7064480

Removed items from the public API
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(none)

Changed items in the public API
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-pub fn backer::nodes::scope<U: 'static, V: 'static>(scope: fn(&mut U) -> &mut V, node: backer::Node<V>) -> backer::Node<U>
+pub fn backer::nodes::scope<T, U: 'static>(scope: impl core::ops::function::Fn(&mut T) -> &mut U + 'static + core::marker::Copy, node: impl core::ops::function::Fn(&mut U) -> backer::Node<U> + 'static + core::marker::Copy) -> backer::Node<T>

Added items to the public API
=============================
(none)

[cyypherus]

Closed in favor of #55