CloneSlicePrelude is now in the prelude, import unnecessary ...
Fix `shadowed lifetimes` warnings ...

Lifetime `'a` declared on functions is shadowing the lifetime `'a` decl.
by the struct.

However all these lifetimes can be inferred by lifetime ellision, so
they can be eliminated entirely.
Merge pull request #175 from drbawb/feature/fix-shadow

Latest rust nightly: Shadowed lifetimes & slice prelude