#clone and #dup for Geom::Point3d/Vector3d
Removed Geom::Vector3d#sameaxis?

Geom::Vector3d#sameaxis? did the same as Geom::Vector3d#parallel? - and using "axis" as a term would also have been confusing.
Modified comments to match existing style.
Added #dup and #clone to Sketchup::Color
Merge pull request #1 from thomthom/master

Notes on Point3d and Vector3d.