Rotation2 and Rotation3 improved with from_* methods. Betwee_vecs implemented for all rotations.
Merge pull request #39 from kvark/t-quat-arc

between_vecs implementation, Rotation traits improvement
Merge pull request #38 from rsaarelm/master

Axis-aligned boxes use top and bottom corners
replace fmt::Default with fmt::Show
Merge pull request #41 from rlane/fmt-show

replace fmt::Default with fmt::Show
Utility methods for AA boxes
Translate method for AABBs
Translate and scale methods for AABB
to_str for Aabbs