For sake of readability and consistency with the standard library macros
assert! and assert_eq!, the macros assert_approx_eq! and assert_approx_eq_eps!
have been implemented based on the ApproxEq trait.
Upon failure these macros yield readable error messages including the input
values and the tolerance (epsilon) used to determine their approximate
equality.
Resolves#131.
I did not have much luck getting the old from_eular logic work the way I
expected so I updated the implementation to match my sources.
I believe this changed the order of the axis, I am unsure of what they were
before.
