Fix test for slerp (#85)

* fix test for slerp

* add scale parameter for slerp test

Author: hyrodium

test/Quaternion.jl

@@ -602,10 +602,9 @@ Base.:(/)(a::MyReal, b::Real) = a.val / b
                 @test slerp(a, b, 0.0).norm
                 @test slerp(a, b, 1.0).norm
                 @test slerp(a, b, 0.5).norm
-                for _ in 1:100
+                for _ in 1:100, scale in (1, 1e-5, 1e-10)
                     q1 = quat(1, 0, 0, 0.0)
-                    # there are numerical stability issues with slerp atm
-                    θ = clamp(rand() * 3.5, deg2rad(5e-1), π)
+                    θ = rand() * π * scale
                     ax = randn(3)
                     q2 = qrotation(ax, θ)
                     qsmall = qrotation(ax, cbrt(eps()))