Library N3662, C++ Dynamic Arrays

Includes the following editorial fixes relative to the proposal:
 - Remove Allocator template parameter from comparison operators.
 - Use `template <class T>` instead of `template< typename T >`.
 - Declare member types public.
 - Refer to 23.2 for implementation-defined iterator types.
 - Add `explicit` keyword to first declaration in [dynarray.cons].