pga3d refactoring

Refactor pga3d module, update scala and sbt versions.

now all pga3d classes have prefix Pga3d, for example Pga3dVector.
In addition, Point and Vector are stored as dual representation with w,x,y,z coordinates. They have getters for real values of wyz, wxz, wxy and xyz.

Because of this conversion some bugs theoretically are possible, but I hope that I have found all of them.