Build error due to `is_sorted` on nightly Rust

[rsammelson]

It looks like is_sorted has been stabilized (rust-lang/rust#128279), and the methods in polyfill.rs are now problematic because they have the same name as the methods on the std iterator trait.

[ripytide]

I've fixed the error and published v0.0.5 for btree_monstrousity and updated the dependencies and published v0.9.2 for nodit.