Try out some collection traits about collect-rs

[apasel422]

I'm working on some map stuff for this, inspired by @gankro's post Replace Most of the Collections API with ranges and iterators.

[Gankra]

One issue with my proposal of having a Get/Remove/Insert traits is that the semantics for remove and insert are different for Maps and Sequences. Panic vs Option.

[apasel422]

See https://github.com/apasel422/eclectic.

This is very much a work in progress, and there are certain bugs with associated types that are preventing me from organizing this exactly the way I want. I opted to separate mutable functionality into separate traits, though there is an argument to be made for combining them.

I will be adding additional constraints for indexing and iteration (all three modes) in the future.

I also need to figure out a solution to the iterator discrepancy between maps like TreeMap and TrieMap (the former yields (&K, &V), while the latter yields (usize, &V)). I have an idea for how to fix this using a Borrow bound on an associated IterKey type that would default to &K once we have default associated types, but the solution currently involves an extra lifetime parameter on Map that ends up propagating to all four map traits. I'll demonstrate this in another branch.

[apasel422]

rust-lang/rust#20671 is also holding things up.