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.
One of the terms in m[0][0] and m[1][1] was incorrectly negated from an
incomplete factorisation when I transcribed the formula.
Also reintroduces the axis-rotation tests which inadvertantly had zero
magnitudes.
comparison of floating point values is inexact and there isn't an easy
way for providing an ULP delta via the TAP interface. morever, the
general expected error is too large to reliably express in ULPs.
