make all Ext methods default impls for DRY and to future-proof for specialization
add utility iterators like . Bonus  adaptor for test
style cleanup
kill IteratorExt, add Cloned
derive all the traits, remove stability markers
globalize issue ref
Merge pull request #6 from Gankro/cleanup

Cleanup Ext + Add utility iterators
(chore) Relicense as dual APACHE and MIT.

Fixes #7
fix license to something crates.io will accept