Array: Simplify around unsafe
Move Indexes to its own file
Array: Move some trait impls into separate file
Array: move format traits to separate file
Simplify one-dimensional iterators, use Elements
Remove itertools dependency
Array: Move Index, IndexMut to arraytraits.rs
Move iterator implementations to iterators.rs
Sharpen up unsafety: Baseiter is unsafe to create

From baseiter comes the lifetime and mut/immut, so creating it is unsafe
and it must have the right parameters.
Array: add Array::map(f: |&A| -> B) -> Array<B>
Array: add examples to .swap_axes and edit others
Array: never fail in PartialEq/Eq. Just return false for other shapes.
Array: add method .allclose()
Array: doc for .diag_iter()
Add tests/complex.rs