dot-dsl: Use zip instead of enumerate + map-with-indexing (#817)
dot-dsl: Use zip instead of enumerate + map-with-indexing (#817)

Notice that we are iterating over two collections in lock-step. `zip` is
the more concise and idiomatic way of expressing this simultaneous
iteration, rather than `enumerate` + `map` that uses the index.

Note that the original also triggers a Clippy suggestion:
https://travis-ci.org/exercism/rust/builds/517554492
warning: an inclusive range would be more readable
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#range_plus_one

Instead of fixing it with `&attributes[i..=i]`, we decided `zip` was better.
exercism/xrust,exercism/xrust,petertseng/exercism-rust,petertseng/exercism-rust,petertseng/exercism-rust