lentrait 0.2.2

A trait for implementing len(), hopefully replacing the unmaintained len_trait crate.
Documentation
# lentrait

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This is a Len trait for Rust, providing a len() function.

This aims to be a unified place to implement Len, so please make a PR if you want to implement it on any new types. 
The old len_trait does not seem to be maintained, so I made this one as a replacement.

Again, WIP so please feel free to contribue. Any code or ideas are welcome!