Remove need for allocation inside Reader

[rylev]

This should be easier to understand, less code, have less rightward drift, completely eliminate all allocation, and be much less hacky than some alternatives.

[kennykerr]

Sweet - thanks!

[kennykerr]

Here's another related case:

windows-rs/crates/libs/metadata/src/reader/tree.rs

Lines 21 to 24 in 0421721

	pub fn flatten(&self) -> Vec<&Tree> {
	// TODO: surely there's a way to do this without a ton of intermediate Vec's...
	std::iter::once(self).chain(self.nested.values().flat_map(|tree| tree.flatten())).collect()
	}