3D unit vectors in ThreeD.Vector
Add spherical and fromSpherical, 3D analogues to direction and fromDirection
new function angleBetween for 3D
3D rotation Transformations in ThreeD.Transform
Rexport angle functions, types from ThreeD.Types
Expose ThreeD.Vector, ThreeD.Transform
correct documentation of aboutZ, aboutX, aboutY
angleRatio calculates ratio between two angles

closes #109
reexport angleRatio from 3D Types
Initial Direction class, with instance Polar, and conversion to / from R3

use Direction instead of R3 in rotationAbout
doc: aboutZ is not called rotate
[ci skip]
rename Polar to Spherical
Merge pull request #107 from diagrams/threeD-util

3D utility functions