views should not do elementwise comparisons for equality operators.
they are pairs of iterators and are only equal if their iterators are
equal.
instead, use `equal` for elementwise equality. we update the name of
exactly_equal to perform this operation too.
we remove some duplicate and specific logical comparator specialisations
and instead rely on a base view/view comparator implementation by way of
make_view.
The coordinate system was unable to support types that prohibited
redim or retype operations. Additionally, the `tags' type used for
providing named data parameters was unwiedly.
We remove much of the dependance on template template parameters in the
defined operations and instead define these in terms of a template
specialisation of is_coord.
The tag types were replaced with direct specialisation of the `store'
struct by the primary type, and passing this type through use of the
CRTP.
